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‌SPECIFICATIONS

ENGINE

Engine Heating and Cooling - Volt

TEMPERATURE VERSUS RESISTANCE (RADIATOR COOLANT TEMPERATURE SENSOR)

FASTENER SPECIFICATIONS

Single Use Non-Threaded Fasteners/Components

Single Use Threaded Fastener/Component Tightening Specifications

Reusable Threaded Fastener Tightening Specifications

APPROXIMATE FLUID CAPACITIES

ADHESIVES, FLUIDS, LUBRICANTS, AND SEALERS

SCHEMATIC WIRING DIAGRAMS

ENGINE HEATING/COOLING WIRING SCHEMATICS

Engine Cooling Fans

Fig. 1: Engine Cooling Fans

Courtesy of GENERAL MOTORS COMPANY

DIAGNOSTIC INFORMATION AND PROCEDURES

DTC P00B3 OR P00B4: RADIATOR COOLANT TEMPERATURE (RCT) SENSOR CIRCUIT LOW/HIGH VOLTAGE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P00B3

Radiator Coolant Temperature (RCT) Sensor Circuit Low Voltage

DTC P00B4

Radiator Coolant Temperature (RCT) Sensor Circuit High Voltage

Diagnostic Fault Information

Typical Scan Tool Data

Radiator Coolant Temperature Sensor

Circuit/System Description

NOTE: The radiator coolant temperature sensor is referred to as B203 Engine Coolant Temperature Sensor 2 in schematics and other areas.

The radiator coolant temperature (RCT) sensor is a variable resistor that measures the temperature of the engine coolant in the radiator. The engine control module (ECM) supplies 5 volts to the RCT signal circuit and supplies a ground to the low reference circuit.

The following table illustrates the difference between temperature, resistance, and voltage:

Conditions for Running the DTC

P00B3

The engine run time is greater than 10 s.

The intake air temperature (IAT) is colder than 70°C (158°F). The DTC runs continuously when the above conditions are met.

P00B4

The engine run time is greater than 60 s.

The intake air temperature (IAT) is warmer than -7°C (19°F). The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P00B3

The ECM detects that the RCT sensor is warmer than 149°C (300°F) for greater than 10 s.

P00B4

NOTE: The scan tool only displays to -40°C (-40°F).

The ECM detects that the RCT sensor is colder than -60°C (-76°F) for greater than 10 s.

Action Taken When the DTC Sets

DTCs P00B3 and P00B4 are Type B DTCs.

The cooling fans will be commanded ON by the ECM. The Engine Coolant Temperature Gauge is inoperative. The AC compressor will be commanded OFF.

Conditions for Clearing the MIL/DTC

DTC P00B3 and P00B4 are Type B DTCs.

Diagnostic Aids

NOTE: The engine coolant temperature (ECT) sensor is mounted on the engine and the radiator coolant temperature (RCT) sensor is mounted on the radiator.

As the thermostat opens, the RCT sensor temperature should rise steadily, then stabilize once the

thermostat opens completely.

Test the RCT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor.

If the vehicle has sat for greater than 8 hours, the RCT sensor and the ECT sensor values should display within 3°C (5°F).

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Hybrid Modes of Operation Description

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine Running.

2. Verify the scan tool Radiator Coolant Temperature Sensor parameter is between -39 to + 120°C (-38 to

+248°F) and changes with engine run time.

If not between -39 to + 120°C (-38 to +248°F) or does not change

Refer to Circuit/System Testing.

If between -39 to + 120°C (-38 to +248°F) and changes

3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

4. Verify the DTC does not set.

If the DTC sets

Refer to Circuit/System Testing.

If the DTC does not set

5. All OK.

Circuit/System Testing

1. Vehicle Off, disconnect the harness connector at the B203 Engine Coolant Radiator Temperature Sensor. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 2 Ω between the low reference circuit terminal 2 and ground.

If 2 Ω or greater

1. Vehicle Off, disconnect the X1 harness connector at the K20 Engine Control Module.

2. Test for less than 2 Ω in the low reference circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K20 Engine Control Module.

If less than 2 Ω

3. Vehicle in Service Mode.

4. Verify the scan tool Radiator Coolant Temperature Sensor parameter is colder than -39°C (-38°F).

If warmer than -39°C (-38°F)

1. Vehicle Off, disconnect the X1 harness connector at the K20 Engine Control Module.

2. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module.

If colder than -39°C (-38°F)

5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.

6. Verify the scan tool Radiator Coolant Temperature Sensor parameter is warmer than 140°C (284°F).

If colder than the 140°C (284°F)

1. Vehicle Off, disconnect the X1 harness connector at the K20 Engine Control Module, Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V

3. Vehicle Off.

4. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K20 Engine Control Module.

If warmer than 140°C (284°F)

7. Test or replace the B203 Engine Coolant Radiator Temperature Sensor.

Component Testing

1. Vehicle Off, remove the B203 Engine Coolant Radiator Temperature Sensor.

NOTE: A thermometer can be used to test the sensor off the vehicle.

2. Test the B203 Engine Coolant Radiator Temperature Sensor by varying the sensor temperature while measuring the sensor resistance. Compare the readings with the Temperature Versus Resistance (Radiator Coolant Temperature Sensor) table and verify that the resistance is within 5 percent of the specification.

If not within the specified range, replace the B203 Engine Coolant Radiator Temperature Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Engine Coolant Temperature Sensor Replacement - Water Outlet

for Radiator Coolant Temperature Sensor replacement.

Control Module References for ECM replacement, programming, and setup.

DTC P00B7: ENGINE COOLANT FLOW INSUFFICIENT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P00B7

Engine Coolant Flow Insufficient

Circuit Description

The engine control module (ECM) monitors the temperature of the engine radiator coolant. The ECM controls the thermostat with a pulse width modulated (PWM) signal. The ECM compares the radiator coolant temperature to the engine coolant temperature in order to determine if there sufficient coolant flow through the thermostat.

Conditions for Running the DTC

DTCs P00B3, P00B4, P00B6, P0116, P0117, and P0118 are not set.

The engine run time is greater than 45 s.

The engine coolant temperature is greater than 70°C (158°F). The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

NOTE: The scan tool display range is between -40 and + 150°C (-40 and +302°F).

The ECM detects the difference between the RCT sensor and the ECT sensor is greater than 45°C (81°F) when the ECT sensor is warmer than 117°C (242°F) for greater than 5 s.

Action Taken When the DTC Sets DTC P00B7 is a Type B DTC. Conditions for Clearing the MIL/DTC DTC P00B7 is a Type B DTC. Diagnostic Aids

The thermostat has a mechanical fail-safe in case of an electrical condition with the thermostat heater.

The mechanical thermostat will open at approximately 80°C (176°F). The mechanical thermostat will cycle from approximately 85°C (185°F) to approximately 102°C (215°F).

A resistance condition in the RCT sensor circuits may cause this DTC. This condition results in a greater voltage on the RCT sensor signal circuit, which is interpreted by the ECM as a colder RCT.

Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine Running.

2. Verify DTC P00B3, P00B4, P00B6, P0116, P0117 or P0118 is not set.

If the DTC is set.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

If the DTC is not set.

3. Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks.

If a condition is found.

Refer to Cooling System Draining and Filling, and Loss of Coolant.

If a condition is not found.

4. Verify the engine cooling fan operates when commanding the cooling fan to 90% and back to 20% with a scan tool.

If the cooling fan does not operate

Refer to DTC P1485-P1487.

If the cooling fan operates

5. Engine Running for 15 min with the A/C OFF.

NOTE: Depending on ambient temperature, it may take up to 4 minutes for the temperature to decrease less than the specified value.

6. Command the Engine Coolant Thermostat Heater to 100 percent with a scan tool, depress the accelerator pedal.

7. Verify the scan tool ECT Sensor parameter decreases to less than 85°C (185°F).

If ECT is warmer than 85°C (185°F)

Refer to Circuit/System Testing.

If ECT is colder than 85°C (185°F)

8. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

9. Verify the DTC does not set.

If the DTC sets

Refer to Circuit/System Testing.

If the DTC does not set

10. All OK.

Circuit/System Testing

1. Vehicle OFF, inspect the cooling system for the conditions below. Refer to Symptoms - Engine Cooling. Weak coolant solution

Obstructed radiator air flow or bent radiator fins Blocked cooling system passages

Radiator hoses that are restricted, collapsed, or deteriorated Damaged water pump and or belt

Loss of cooling system pressure Leaking surge tank cap

Radiator hoses

Cylinder head or an engine block that is cracked or plugged

If a condition is found

Repair as necessary.

If a condition is not found

2. Replace the Engine Coolant Thermostat.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Engine Coolant Thermostat Housing Replacement for engine coolant thermostat replacement.

DTC P0597-P0599: ENGINE COOLANT THERMOSTAT HEATER CONTROL CIRCUIT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0597

Engine Coolant Thermostat Heater Control Circuit

DTC P0598

Engine Coolant Thermostat Heater Control Circuit Low Voltage

DTC P0599

Engine Coolant Thermostat Heater Control Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

A wax pellet-type thermostat controls the flow of the engine coolant through the engine cooling system. The wax element of the thermostat expands and opens the thermostat when it is heated. The engine coolant thermostat heater uses an electric heating element to help heat the wax pellet opening the thermostat to increase cooling system performance during certain operation conditions. Ignition voltage is supplied directly to the thermostat heater through a fuse. If certain driving conditions are met the engine control module (ECM) controls the thermostat heater by providing a pulse width modulated (PWM) ground.

Conditions for Running the DTCs

The ignition is ON, or the engine is running.

The DTCs run continuously once the above condition is met

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 15 seconds.

Action Taken When the DTC Sets

DTCs P0597, P0598, and P0599 are Type B DTCs.

The engine control module commands the engine cooling fans ON.

Conditions for Clearing the DTC

DTCs P0597, P0598, and P0599 are Type B DTCs.

Diagnostic Aids

A low engine coolant level could cause the thermostat heater to overheat and set a DTC.

Without electric assist the wax pellet thermostat begins to open at 103° C (217° F) and is fully open at 117° C (243° F) when the electric energy not assisted.

The mechanical thermostat will open at approximately 80°C (176°F). The mechanical thermostat will cycle from approximately 85°C (185°F) to approximately 102°C (215°F).

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Hybrid Modes of Operation Description

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks.

If a condition is found

Refer to Cooling System Draining and Filling, and Loss of Coolant.

If a condition is not found

2. Vehicle in Service Mode.

3. Verify the parameters listed below do not display Malfunction when commanding the Engine Coolant Thermostat Heater 0% - 100% with a scan tool.

Engine Coolant Thermostat Heater Control Circuit Low Voltage Test Status Engine Coolant Thermostat Heater Control Circuit Open Test Status

Engine Coolant Thermostat Heater Control Circuit High Voltage Test Status

If Malfunction is displayed

Refer to Circuit/System Testing.

If Malfunction is not displayed

4. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

5. Verify the DTC does not set.

If any DTC sets

Refer to Circuit/System Testing.

If the DTC does not set

6. All OK.

Circuit/System Testing

1. Vehicle OFF, disconnect the harness connector at the E41 Engine Coolant Thermostat Heater.

2. Vehicle in Service Mode

3. Verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle OFF, remove the test lamp.

2. Test for less than 2 Ω in the ignition circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω verify the fuse is not open and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

NOTE: The ignition circuit may supply voltage to other components. Make sure to test all circuits and components for a short to ground that share the ignition circuit.

1. Vehicle OFF, remove the test lamp, and disconnect all components on the circuit.

2. Test for infinite resistance between the ignition circuit and ground

If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance

3. Replace the fuse, vehicle in Service Mode.

4. Verify the fuse is good after connecting each of the components one at a time.

If the fuse opens, replace the component that opens the fuse when connected. If the fuse is good, all OK.

If the test lamp illuminates

4. Connect a test lamp between the ignition circuit terminal 1 and the control circuit terminal 2, command the Engine Coolant Thermostat Heater to Increase to 100 % and Decrease to 0 % with a scan tool.

5. Verify that a test lamp turns ON and OFF.

If the test lamp is always ON

1. Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module.

2. Test for infinite resistance between the control circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module.

If the test lamp is always OFF

1. Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the control circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V.

3. Test for less than 2 Ω in the control circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω replace the K20 Engine Control Module

If the test lamp turns ON and OFF

6. Test or replace the E41 Engine Coolant Thermostat Heater.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Engine Coolant Thermostat Housing Replacement

Control Module References for control module replacement, programming, and setup

DTC P112F: RADIATOR COOLANT TEMPERATURE SENSOR NOT PLAUSIBLE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P112F

Radiator Coolant Temperature Sensor Not Plausible

Diagnostic Fault Information

Typical Scan Tool Data

Radiator Coolant Temperature Sensor

Circuit Description

The engine coolant radiator temperature sensor is a variable resistor that measures the temperature of the engine coolant in the radiator. The engine control module (ECM) supplies 5 volts to the engine coolant radiator temperature signal circuit and supplies a ground to the low reference circuit. The purpose of this diagnostic is to determine if the input from the RCT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the engine is OFF. If the required engine OFF time is met at start-up, the ECM will compare the temperature difference between the actual measured RCT and ECT sensors.

The following table illustrates the difference between temperature, resistance, and voltage:

Conditions for Running the DTC

DTCs P00B3, P00B4, P0112, P0113, P0117, P0118, P0502, P0503, P111E or P2610 are not set.

The vehicle has been OFF for greater than 8 hours before vehicle ON.

The engine is running.

The intake air temperature (IAT) is warmer than -7°C (19°F). The fuel level is greater than 10 percent.

The DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM determines the absolute difference of temperature between the RCT start up temperature and ECT start up temperature is greater than 20°C (68°F).

Action Taken When the DTC Sets DTC P112F is a Type B DTC. Conditions for Clearing the MIL/DTC DTC P112F is a Type B DTC. Diagnostic Aids

As the thermostat opens, the radiator coolant temperature sensor signal should rise steadily, then stabilize once the thermostat opens completely.

Inspect for the correct operation of the engine cooling system and verify the correct coolant level.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify the scan tool Radiator Coolant Temperature Sensor parameter is between -39 to + 120°C (-38 to

+248°F) and changes with engine run time.

If not between -39 to + 120°C (-38 to +248°F) or does not change

Refer to Circuit/System Testing.

If between -39 to + 120°C (-38 to +248°F) and changes

3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

4. Verify the DTC does not set.

If the DTC sets

Refer to Circuit/System Testing.

If the DTC does not set

5. All OK.

Circuit/System Testing

1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B203 Engine Coolant Radiator Temperature Sensor. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 5 Ω between the low reference terminal 2 and ground.

If 5 Ω or greater

1. Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module.

2. Test for less than 2 Ω in the low reference circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K20 Engine Control Module.

If less than 5 Ω

3. Vehicle in Service Mode.

4. Verify the scan tool Radiator Coolant Temperature Sensor parameter is colder than -39°C (-38°F).

If warmer than -39°C (-38°F)

1. Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module.

2. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module.

If colder than -39°C (-38°F)

5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2, Vehicle in Service Mode.

6. Verify the scan tool Radiator Coolant Temperature Sensor parameter is warmer than 140°C (284°F).

If colder than the 140°C (284°F)

1. Vehicle OFF, disconnect the harness connector at the K20 Engine Control Module, Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V

3. Vehicle OFF

4. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K20 Engine Control Module.

If warmer than 140°C (284°F)

7. Test or replace the B203 Engine Coolant Radiator Temperature Sensor.

Component Testing

1. Vehicle OFF, remove the B203 Engine Coolant Radiator Temperature Sensor.

NOTE: A thermometer can be used to the used to test the sensor off the vehicle.

2. Test the engine coolant radiator temperature sensor by varying the sensor temperature while measuring the sensor resistance. Compare the readings with the Temperature Versus Resistance (Radiator Coolant Temperature Sensor) table and verify that the resistance is within 5 percent of the specification.

If not within the specified range, replace the B203 Engine Coolant Radiator Temperature Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Engine Coolant Temperature Sensor Replacement - Radiator

Control Module References for control module replacement, setup, and programming

DTC P1485-P1487: COOLING FAN OUTPUT CIRCUIT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P1485

Cooling Fan Output Circuit

DTC P1486

Cooling Fan Output Circuit Low Voltage

DTC P1487

Cooling Fan Output Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

The hybrid/EV powertrain control module 2 indirectly controls the radiator fans. When propulsion is active, the engine control module (ECM) processes all requests for the cooling fans to be turned ON regardless of which module originates the request. The ECM decides if and at what speed the cooling fans should operate. The ECM sends the cooling fan command to the hybrid/EV powertrain control module 2. The hybrid/EV powertrain control module 2 sends the signal to the cooling fans to operate and at what speed. If the vehicle is in Charge Mode and the hybrid/EV powertrain control module 2 requests the cooling fans to operate and the ECM is not awake, the hybrid/EV powertrain control module 2 will control the cooling fans without ECM intervention.

The ECM communicates the fan command PWM signal to the hybrid/EV powertrain control module 2 through the cooling fan speed signal circuit/hardwire circuit and also sends a redundant serial data signal. Since the hardwire circuit is an output from the ECM but an input to the hybrid/EV powertrain control module 2, each module has unique DTCs to monitor the same circuit.

Conditions for Running the DTC

DTC P2537 is not set.

The 12 V battery voltage is equal to or greater than 11 V. The accessory circuit is active for greater than 5 s.

The DTCs run continuously when the conditions above are met.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the output circuit do not match for greater than 5 s.

Action Taken When the DTC Sets

DTCs P1485, P1486 and P1487 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P1485, P1486 and P1487 are Type B DTCs.

Diagnostic Aids

DTCs P1485, P1486 and P1487 will not keep the cooling fans from operating. If one of these DTCs is set the HPCM 2 will command the cooling fans to 90%. If the cooling fans do not operate, refer to DTC P148A- P148C for further diagnosis.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Hybrid Modes of Operation Description

Hybrid/EV Cooling System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle ON.

2. Verify DTC P1485, P1486, P1487, P148A, P148B, or P148C is not set.

If the DTC is set

Refer to Circuit/System Testing.

If the DTC is not set

3. All OK.

Circuit/System Testing

1. Vehicle OFF, disconnect the X2 harness connector at the K114B Hybrid/EV Powertrain Control Module 2, vehicle in Service Mode.

NOTE: The cooling fan circuit is pulled up to a voltage within the ECM. 3 - 4 V measured on this circuit with the hybrid/EV powertrain control module 2 disconnected is normal.

2. Test for 3 - 4 V between the cooling fan circuit terminal 9 and ground.

If less than 3 V

1. Vehicle OFF, disconnect the X1 harness connector at the K20 Engine Control Module.

2. Test for infinite resistance between the cooling fan circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K20 Engine Control Module.

If 4V or greater

1. Vehicle OFF. Disconnect the X1 harness connector at the K20 Engine Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the cooling fan circuit and ground. If greater than 1 V, repair the short to voltage on the circuit. If 1 V or less, replace the K20 Engine Control Module.

If 3 - 4 V

3. Vehicle OFF, disconnect the X1 harness connector at the K20 Engine Control Module.

4. Reconnect the K114B Hybrid/EV Powertrain Control Module 2 connector X2.

5. Vehicle in Service Mode. Test for greater than 10 V between the signal circuit and ground.

If 10 V or less

Replace the Hybrid/EV Powertrain Control Module 2.

If greater than 10 V

6. Replace the K20 Engine Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for engine control module or hybrid powertrain control module 2 replacement, programming and setup

DTC P2181: ENGINE COOLING SYSTEM PERFORMANCE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P2181

Engine Cooling System Performance

Circuit/System Description

The engine control module (ECM) monitors temperature difference between the engine coolant temperature (ECT) sensor and the radiator coolant temperature (RCT) sensor during a cold start-up. The purpose of this diagnostic is to analyze the engine coolant thermostat for being stuck open.

Conditions for Running the DTC

DTCs P00B3, P00B4, P00B6, P0101, P0102, P0103, P0111, P0112, P0113, P0114, P0116, P0117 or

P0118 are not set.

The vehicle has had a minimum ignition OFF time of 7 h. The engine run time is between 50 s and 23 min.

The engine coolant temperature (ECT) sensor at start-up is between -10° C and 59° C (14° F and 138° F).

The intake air temperature (IAT) sensor is between -7° C and 60° C (19° F and 140° F). The Engine Coolant Thermostat Heater Command is less than 50 %.

The Ethanol in the fuel is less than 87 %.

The airflow into the engine is between 1 and 100 g/s.

The DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM detects the engine coolant thermostat is stuck open for at least 2.5 min.

Action Taken When the DTC Sets DTC P2181 is a Type B DTC Conditions for Clearing the DTC DTC P2181 is a Type B DTC Diagnostic Aids

Insufficient vehicle interior heating is an indication of improper thermostat operation.

The scan tool Desired ECT Sensor and the ECT Sensor parameters should be within 5° C (41° F) when the engine is at operating temperature.

A resistance condition in the ECT sensor circuits may cause this DTC. This condition results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cooling System Description and Operation Hybrid Modes of Operation Description

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine Running.

2. Verify DTC P00B3, P00B4, P00B6, P0116, P0117, P0118, or P0119 is not set.

If the DTC is set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

If the DTC is not set

3. Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks.

If a condition is found

Refer to Cooling System Draining and Filling, and Loss of Coolant.

If a condition is not found

4. Engine Running for 15 min with the A/C OFF.

5. Command the Engine Coolant Thermostat Heater to 0 % with a scan tool, depress the accelerator pedal for 5 min.

6. Verify the scan tool ECT Sensor parameter is between 80° C and 102° C (176° F and 215° F).

If ECT sensor parameter is not between 80° C and 102° C (176° F and 215° F)

Replace the engine coolant thermostat.

If ECT sensor parameter is between 80° C and 102° C (176° F and 215° F)

7. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

8. Verify the DTC does not set.

If the DTC sets

Refer to step 1.

If the DTC does not set

9. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Engine Coolant Thermostat Housing Replacement for engine coolant thermostat replacement.

SYMPTOMS - ENGINE COOLING

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following:

Perform Diagnostic System Check - Vehicle and verify all of the following items:

Ensure that the engine control module (ECM) and indicator lamp are operating correctly. Ensure that there are no diagnostic trouble codes (DTCs) that are stored.

Scan tool data is within a normal operating range.

Verify the customer concern.

Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.

Locate the correct symptom. Perform the tests and inspections associated with the symptom.

Review the entire cooling system operation in order to familiarize yourself with the system functions. Refer to

Cooling System Description and Operation, and Hybrid/EV Cooling System Description and Operation .

Visual/Physical Inspection

CAUTION: Use the connector test adapter kit EL-35616-F for any test that requires probing the following items:

The control module harness connectors The electrical center fuse/relay cavities The component terminals

The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

Several of the symptom procedures call for a careful visual and physical inspection. This can lead to correcting a condition without further tests and can save time. This inspection should include the following areas:

Ensure that all control module grounds are clean, tight, and correctly located.

Inspect cooling system hoses and pipes for splits, kinks, and proper connections. Inspect thoroughly for any type of a leak or a restriction.

Inspect for a dirty or restricted engine cooling radiator and HVAC condenser.

Inspect for aftermarket devices which could affect the operation of the Cooling System.

Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Inspect the surge tank reservoirs for the proper coolant level.

Identifying Intermittent Conditions

Many intermittent conditions occur with harness or connector movement due to engine torque, rough pavement, vibration or physical movement of a component. Refer to the following for a list to help isolate an intermittent condition:

Moisture and water intrusion in connectors, terminals, and components Connector mating

Terminal contact

High circuit or component resistance - High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.

Harness' that are routed too tight, or chaffed circuits High or low ambient temperature

High or low engine coolant temperatures High underhood temperatures

Heat build up in component or circuit due to circuit resistance, poor terminal contact, or high electrical load

High or low system voltage High vehicle load conditions Rough road surface

Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge Incorrect installation of non-factory, aftermarket, and after factory add on accessories

If an intermittent is detected, refer to Testing for Intermittent Conditions and Poor Connections for specific strategies in diagnosing intermittent conditions.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

DTC P148A-P148C

Engine Overheating Loss of Coolant

Thermostat Diagnosis

Engine Fails To Reach Normal Operating Temperature

COOLING FAN INOPERATIVE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The engine cooling fan system is composed of one electric cooling fan and a cooling fan control module. The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal, which enables cooling fan operation at variable speeds. The ECM will only operate the cooling fan at certain percentages to prevent undesirable noise and vibration. The cooling fan control module is thermally protected to prevent module damage in the case of a short circuit condition in the cooling fan motor.

Diagnostic Aids

The cooling fan will not operate when the scan tool Cooling Fan Motor Command parameter displays less than 4 %. This is a normal condition.

A delay or ramp up of approximately 12 seconds may occur before the cooling fan activates or changes speed when being commanded with a scan tool.

The cooling fan Control Function operates as described below when the ignition is ON, and engine is OFF:

Command State 1 operates the cooling fan at approximately 18 % Command State 2 operates the cooling fan at approximately 54 % Command State 3 operates the cooling fan at approximately 67 % Command State 4 operates the cooling fan at approximately 85 % Command State 5 operates the cooling fan at approximately 90 %

During normal operating conditions the ECM may initially activate the cooling fan at 4 or 5 % and then increase to the percentages indicated above, as needed, to satisfy powertrain cooling requirements.

Generally, the ECM will operate the cooling fan at the specified percentages but, may scale the percentages either higher or lower in response to generator demand.

When operating the cooling fan with a scan tool, the Commanded States 1 - 5 should be exercised in order, from OFF to High or High to OFF. The cooling fan control module may disable the cooling fan if a Commanded State is skipped.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify that DTC P01485 - P1487

If a DTC is set

Refer to DTC P1485-P1487.

If no DTC is set.

NOTE: A slight delay may occur before the cooling fan activates.

3. Verify the G10 Cooling Fan Motor activates and increases in speed with each command using a scan tool.

The cooling fan does not activate or increase in speed

Refer to Circuit/System Testing

The cooling fan activates and increases in speed

4. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector G10 Cooling Fan Motor.

2. Verify that a test lamp illuminates between the ground circuit terminal 2 and B+.

If the test lamp does not illuminate

1. Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If the test lamp illuminates

3. Test or replace the G10 Cooling Fan Motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Coolant Fan Shroud Replacement for G10 Cooling Fan Motor replacement.

Control Module References

ENGINE OVERHEATING

LOSS OF COOLANT

THERMOSTAT DIAGNOSIS

ELECTRICALLY HEATED THERMOSTAT DIAGNOSIS

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The engine cooling system electrically heated thermostat is an integrated part of the thermostat housing. It is not serviced separately. The thermostat contains a wax pellet which expands when electrically energized. The ECM energizes the wax pellet during full load driving, or, when the engine coolant or the ambient temperature is higher. This causes the thermostat to open earlier than it would without electrical assistance.

During normal engine operation, the thermostat begins to open mechanically at 78° C (172° F). When coolant temperature reaches or exceeds 80° C (176° F), the ECM begins to energize the wax pellet to try to maintain coolant temperature at 78° C (172° F).

Diagnostic Aids

A radiator or AC condenser with bent fins or obstructed air flow passages may cause the engine coolant temperature to be too hot.

An incorrect engine coolant mixture may cause the engine coolant to boil at low temperature.

An engine coolant mixture that is contaminated with debris may adversely affect the operation of the cooling system components. Verify that the coolant mixture is not contaminated.

An engine cooling system that has been incorrectly filled or serviced may have air trapped within the system. If the system contains air, the coolant level may appear to be correct while it is actually incorrect. To avoid misdiagnosis, it may be necessary to verify that no conditions have occurred that may cause the cooling system to contain trapped air.

For accurate test results, allow the vehicle to stabilize in an environment where ambient temperature is

between 10 - 27° C (50 - 80° F) for 8 hours prior to testing.

Reference Information

Schematic Reference

Engine Controls Schematics

Engine Heating/Cooling Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References

Circuit/System Verification

1. Ignition ON/ Vehicle in Service Mode.

2. Verify that DTC P00B3, P00B4, P00B6, P00B7, P0116, P0117, P0018, P0119, P0128, P0597, P0598,

P0599, or P2181 is not set.

If DTC P00B3, P00B4, P00B6, P00B7, P0116, P0117, P0018, P0119, P0128, P0597, P0598,

P0599, or P2181 is set.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

If DTC P00B3, P00B4, P00B6, P00B7, P0116, P0117, P0018, P0119, P0128, P0597, P0598,

P0599, or P2181 is not set.

3. Verify the coolant reservoir contains the correct level of engine coolant.

If the coolant level is low

Fill the coolant reservoir to the correct level and pressure test the cooling system and the coolant reservoir cap for a leak. Refer to Cooling System Draining and Filling, and Cooling System Leak Testing. If a leak is found, repair as necessary.

If the coolant level is not low

4. Verify the G10 Cooling Fan Motor activates in each available speed when commanding the cooling fan

ON with a scan tool. The cooling fan speed should increase with each command.

If the cooling fan does not activate or increase in speed as commanded

Refer to Cooling Fan Inoperative

If the cooling fan activates and increases in speed as commanded

5. Close the hood and set the HVAC controls to the OFF position.

6. Start the engine and warm the engine up to operating temperature.

7. Verify the scan tool ECT Sensor parameter displays between 101 - 120° C (214 - 248° F) while the engine is running.

If 121° C (249° F) or greater

Refer to Circuit/System Testing - Engine Coolant Temperature too High.

If 90° C (194° F) or less.

Refer to Circuit/System Testing - Engine Coolant Temperature too Low.

If between 101 - 120° C (214 - 248° F).

8. All OK.

Circuit/System Testing

NOTE: For accurate test results, allow the vehicle to stabilize in an environment where ambient temperature is between 10 - 27° C (50 - 80° F) for 8 hours prior to testing.

Engine Coolant Temperature too High

1. Start the engine and verify the HVAC controls are set to the OFF position.

NOTE: The cooling fan should automatically turn ON when you select Engine Coolant Thermostat Heater.

2. With the scan tool, navigate to Control Functions and select Engine Coolant Thermostat Heater and Cooling Fan. Verify the engine cooling fan turns ON when Engine Coolant Thermostat is selected.

3. Verify the hood is closed.

4. Engine running at 1, 600 RPM, note or record the ECT Sensor parameter value.

NOTE: An engine cooling system that has been incorrectly filled or serviced may have air trapped within the system. If the system contains air, the coolant level may appear to be correct while it is actually incorrect. For accurate test results, it may be necessary to verify that no conditions have occurred that may cause the system to contain trapped air.

Depending on ambient temperature, it may take up to 4 minutes for the temperature to decrease 10°C (18°F) or greater.

The ECT Sensor parameter value may increase between 3 - 5° C (2 - 9° F) at first. It should then decrease 10°C (18°F) or greater and stabilize.

5. Engine at 2, 000 RPM, verify the ECT Sensor parameter decreases by 10°C (18°F) or greater while commanding the scan tool Engine Coolant Thermostat Heater to 100 %.

If the parameter does not decrease by 10°C (18°F) or greater

Inspect for the conditions listed below and repair as necessary. Refer to Symptoms - Engine Cooling for additional information.

Restricted/plugged radiator

Restricted/plugged radiator hoses Restricted/plugged cylinder head

Restricted/plugged heater core or heater hoses

If none of the conditions listed above exist, replace the E41 Engine Coolant Thermostat.

NOTE: If the thermostat is intermittently sticking closed, it may be necessary to repeat the Circuit/System Verification and Circuit/System Testing.

If the parameter decreases by 10° C (18° F) or greater

6. All OK.

Engine Coolant Temperature too Low

NOTE: For accurate test results, allow the vehicle to stabilize in an environment where ambient temperature is between 10 - 27° C (50 - 80° F) for 8 hours prior to testing.

NOTE: Information for the following test may be in GDS stored data from the Circuit/System Verification.

1. Verify the hood is closed.

2. Start the engine and set the HVAC controls to the OFF position.

3. Engine idling, verify the scan tool ECT Sensor parameter reaches between 90 - 100° C (194 - 212° F) within the guidelines listed below:

At 27° C (80° F) ambient temperature, the parameter should reach 85° C (185° F) in 18 minutes or less.

At 20° C (68° F) ambient temperature, the parameter should reach 85° C (185° F) in 22 minutes or less.

At 10° C (50° F) ambient temperature, the parameter should reach 85° C (185° F) in 26 minutes or less.

If the parameter does not display 85° C (185° F) within the guidelines listed above

Replace the E41 Engine Coolant Thermostat.

If the parameter displays between 85° C (185° F) within the guidelines listed above

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Engine Coolant Thermostat Housing Replacement

ENGINE FAILS TO REACH NORMAL OPERATING TEMPERATURE

PRESSURE CAP TESTING

Special Tools

GE-42401-A Radiator Cap and Surge Tank Test Adapter

EN-24460-A Cooling System Pressure Tester

Equivalent regional tools:Special Tools

WARNING: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

1. Remove the pressure cap.

2. Wash the pressure cap sealing surface with water.

Fig. 2: Identifying Pressure Cap Tester Courtesy of GENERAL MOTORS COMPANY

NOTE: Lubricate GE-42401-A radiator cap and surge tank test adapter and pressure cap O-rings with coolant and press cap to seat O-ring on

GE-42401-A radiator cap and surge tank test adapter before turning to engage threads.

3. Use the EN-24460-A cooling system pressure tester (1) with GE-42401-A radiator cap and surge tank test adapter (2) in order to test the pressure cap.

4. Test the pressure cap for the following conditions:

Pressure release when the EN-24460-A cooling system pressure tester exceeds the pressure rating of the pressure cap.

Maintain the rated pressure for at least 10 seconds.

Note the rate of pressure loss.

5. Replace the pressure cap under the following conditions:

The pressure cap does not release pressure which exceeds the rated pressure of the cap. The pressure cap does not hold the rated pressure.

COOLING SYSTEM LEAK TESTING

Special Tools

GE-42401-A Radiator Cap and Surge Tank Test Adapter For equivalent regional tools, refer to Special Tools.

WARNING: Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.

WARNING: In order to help avoid being burned, do not remove the radiator cap while the engine and the radiator are hot. Scalding fluid and steam can be blown out under pressure if the cap is removed too soon.

1. Remove the pressure cap.

2. Test the operation of the pressure cap. Refer to Pressure Cap Testing.

3. Wash the pressure cap mating surface with water.

Fig. 3: J-42401-2 Pressure Test Adapter And Coolant Recovery Reservoir Courtesy of GENERAL MOTORS COMPANY

4. Install the GE-42401-2 pressure test adapter (1) to the coolant recovery reservoir (2) to plug the reservoir bleeder gallery.

Fig. 4: Cooling System Pressure Adapter Courtesy of GENERAL MOTORS COMPANY

5. Use a commercial cooling system pressure adapter (1) and moisten the rubber with coolant fluid.

Fig. 5: Commercial Adapter And Adapter Courtesy of GENERAL MOTORS COMPANY

6. Install the commercial adapter (1) to the GE-42401-3 adapter (2). Use a suitable underlay to be able to use enough force. Inspect the assembly for proper seat then.

Fig. 6: Commercial Cooling System Pressure Tester, Assembled Adapters and Coolant Recovery Reservoir

Courtesy of GENERAL MOTORS COMPANY

7. Install the assembled adapters (3, 4) to the coolant recovery reservoir (5).

8. Install a commercial cooling system pressure tester (1, 2) to the commercial adapter.

NOTE: Do NOT exceed the pressure cap rating.

9. Using the pressure tester apply pressure to the cooling system.

10. Observe the gage of the pressure tester for any loss.

11. The cooling system should hold the rated pressure for at least 2 minutes.

12. Repair any leaks as required.

REPAIR INSTRUCTIONS

HOSE CLAMP REPLACEMENT GUIDELINES - SPRING TYPE

Special Tools

BO-38185 Hose Clamp Pliers

GE-47622 Hose Clamp Pliers.

Equivalent regional tools:Special Tools

Spring Type Hose Clamp Replacement Guidelines

Fig. 7: Spring Type Hose Clamps

Courtesy of GENERAL MOTORS COMPANY

Vehicles utilize spring type hose clamps (1) to secure joints in which fluids, gases, or engine vacuum can travel to various vehicle systems. Spring type hose clamps are engineered to provide the proper amount of tension to maintain a leak & maintenance free joint for the life of the vehicle.

Spring type hose clamps have a special coating applied to the exterior of the clamp that is engineered to resist rust/corrosion, improve durability and increase the life of the hose clamp. If the coating is damaged, rust/corrosion could form resulting in the need to replace the hose clamp.

Many spring type hose clamps within GM utilize a small amount of adhesive placed directly on the hose clamp to secure the clamp to the mating hose for manufacturing purposes. Over time the strength of the adhesive will deteriorate. It is extremely important when a technician is attempting to service a joint or remove the hose clamp, that the clamp is not rotated or repositioned so that is tears and/or damages the hose. In this case, the hose and clamp must both be replaced.

When repairing a vehicle it is very important to observe the condition of both the hose and the spring type hose clamp as well as the orientation of the clamp to the hose.

If the spring type hose clamp(s) have any of the following conditions on any area of the clamp, replace the

clamp(s) immediately.

Rust/Corrosion Cracks

Physical damage

Leakage attributed to the retention of the clamp

Removing The Spring Type Hose Clamp

While keeping the hose stationary, use BO-38185 Hose Clamp Pliers or GE-47622 Hose Clamp Pliers and release the spring type hose clamp tension while attempting to separate the hose clamp from the hose.

If the spring type hose clamp will not easily separate from the hose and/or the clamp tears or damages the hose, both the hose and hose clamp must be replaced

If the spring type hose clamp is easily removed from the hose, the clamp can be reused provided that the clamp does not have any of the conditions as noted above.

If The Spring Type Hose Clamp Is Being Reused

It is extremely important that the spring type hose clamp is orientated to the hose in the exact same position as it was installed during vehicle assembly so that the hose clamp is not damaged or the hose clamp does not contact or damage any adjacent components. Do not use any type of adhesive on the hose clamp prior to installation.

When Reusing The Spring Type Hose Clamp and Replacing The Hose

The inside and outside hose diameter must be identical between the new hose and the existing hose to guarantee proper hose clamp tension and joint integrity.

Always place the existing spring type hose clamp in the same orientation as it was positioned prior to separating the joint. The new hose might have a marking on the hose indicating the correct position of a hose clamp, which should re-confirm the correct hose clamp position. The hose clamp should not contact any adjacent components after installation.

When Reusing The Spring Type Hose Clamp with an Existing Hose

Always place the existing spring type hose clamp in the same orientation as it was positioned prior to separating the joint. The existing hose might have an indentation or compression mark on the hose from where the hose clamp was installed previously. The hose clamp should identically overlay this position. The existing hose might also have a marking on the hose indicating the correct position of the hose clamp, which should re- confirm the correct hose clamp position. The hose clamp should not contact any adjacent components after installation.

If The Spring Type Hose Clamp Is Being Replaced

If the hose clamp needs to be replaced, always replace the hose as part of the service repair. It is extremely important that a new spring type hose clamp is orientated to the hose in the exact same position as it was installed during vehicle assembly so that the hose clamp is not damaged or the hose clamp does not contact or damage any adjacent components. Do not use any type of adhesive on the hose clamp prior to installation.

When Replacing The Spring Type Hose Clamp and Replacing The Hose

The inside and outside hose diameter must be identical between the new hose and the existing hose to guarantee proper hose clamp tension and joint integrity.

Always place the new spring type hose clamp in the same orientation as it was positioned prior to separating the joint. The new hose might have a marking on the hose indicating the correct position of a hose clamp, which should re-confirm the correct hose clamp position. The hose clamp should not contact any adjacent components after installation.

When Replacing The Spring Type Hose Clamp with an Existing Hose

Always place the new spring type hose clamp in the same orientation as it was positioned prior to separating the joint. The existing hose might have an indentation or compression mark on the hose from where a hose clamp was installed previously. The hose clamp should identically overlay this position. The existing hose might also have a marking on the hose indicating the correct position of the hose clamp, which should re-confirm the correct hose clamp position. The hose clamp should not contact any adjacent components after installation.

COOLING SYSTEM DRAINING AND FILLING

Special Tools

GE-26568 Coolant and Battery Tester

GE-47716 Vac-N-Fill Coolant Refill Tool

GE-42401-A Radiator Cap and Surge Tank Test Adapter

Equivalent regional tools:Special Tools

Draining Procedure

WARNING: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

1. To drain the engine radiator, remove the radiator drain cook from the radiator. Refer to Radiator Drain Cock Replacement.

Fig. 8: View Of Venturi Assembly & Vacuum Tank Courtesy of GENERAL MOTORS COMPANY

2. Attach the venturi assembly to the vacuum tank.

Fig. 9: View Of Shop Air Hose & Venturi Assembly Courtesy of GENERAL MOTORS COMPANY

3. Attach a shop air hose to the venturi assembly.

Ensure the valve on the venturi assembly is closed.

4. Attach the vacuum hose to the vacuum tank.

Fig. 10: Attaching Extraction Hose To Vacuum Hose Courtesy of GENERAL MOTORS COMPANY

5. Attach the extraction hose to the vacuum hose.

6. Insert the extraction hose into the radiator outlet front hose until the extraction hose contacts the bottom of the radiator outlet hose.

Fig. 11: Identifying Valve On Venturi Assembly Courtesy of GENERAL MOTORS COMPANY

7. Open the valve on the venturi assembly to start a vacuum draw.

8. Use the extraction hose to draw out coolant until the radiator is empty.

9. The vacuum tank has a drain valve on the bottom of the tank. Open the valve to drain coolant from the vacuum tank into a suitable container for disposal.

10. If a complete engine block drain is required, remove the engine block drain plug.

11. To drain the heater cooling loop, remove the heater inlet hose from the heater cooling heater. Refer to

Heater Inlet Hose Replacement .

12. Inspect the coolant.

13. Follow the appropriate procedure based on the condition of the coolant. Normal in appearance--Follow the filling procedure.

Discolored--Follow the flush procedure. Refer to Flushing

14. After draining the system:

1. Install Radiator Drain Cock Replacement

2. Install Heater Inlet Hose Replacement

Vac-N-Fill Procedure

WARNING: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while the engine and radiator are still hot.

NOTE: To prevent boiling of the coolant/water mixture in the vehicles cooling system, do not apply vacuum to a cooling system above 49°C (120°F). The tool will not operate properly when the coolant is boiling.

Fig. 12: Identifying Vac-N-Fill Cap

Courtesy of GENERAL MOTORS COMPANY

1. Install GE-42401-2 Radiator Cap and Surge Tank Test Adapter into the surge tank fill neck.

2. Install GE-42401-3 Radiator Cap and Surge Tank Test Adapter to the surge tank fill neck.

3. Attach the Vac N Fill cap to the GE-42401-3 Radiator Cap and Surge Tank Test Adapter.

Fig. 13: Attaching The Vacuum Gage Assembly To The Vac-N-Fill Cap Courtesy of GENERAL MOTORS COMPANY

4. Attach the vacuum gauge assembly to the Vac N Fill cap.

Fig. 14: Attaching Fill Hose To Barb Fitting On Vacuum Gage Assembly Courtesy of GENERAL MOTORS COMPANY

5. Attach the fill hose to the barb fitting on the vacuum gauge assembly.

Ensure that the valve is closed.

Fig. 15: View Of Graduated Reservoir & Hose Courtesy of GENERAL MOTORS COMPANY

NOTE: Use a 50/50 mixture of DEX-COOL antifreeze and de-ionized water.

Always use more coolant than necessary. This will eliminate air from being drawn into the cooling system.

6. Pour the coolant mixture into the graduated reservoir.

7. Place the fill hose in the graduated reservoir.

NOTE: Prior to installing the vacuum tank onto the graduated reservoir, ensure that the drain valve located on the bottom of the tank is closed.

8. Install the vacuum tank on the graduated reservoir with the fill hose routed through the cut-out area in the vacuum tank.

Fig. 16: View Of Venturi Assembly & Vacuum Tank Courtesy of GENERAL MOTORS COMPANY

9. Attach the venturi assembly to the vacuum tank.

Fig. 17: View Of Shop Air Hose & Venturi Assembly Courtesy of GENERAL MOTORS COMPANY

10. Attach a shop air hose to the venturi assembly.

Ensure the valve on the venturi assembly is closed.

Fig. 18: Attaching Vacuum Hose To Vacuum Gauge Assembly & Vacuum Tank Courtesy of GENERAL MOTORS COMPANY

11. Attach the vacuum hose to the vacuum gauge assembly and the vacuum tank.

12. Position the passenger compartment heater coolant control solenoid valve to normal using GDS. The hybrid powertrain control module 2 controls the passenger compartment heater coolant control solenoid Valve

Fig. 19: Identifying Valve On Venturi Assembly Courtesy of GENERAL MOTORS COMPANY

13. Open the valve on the venturi assembly. The vacuum gauge will begin to rise and a hissing noise will be present.

Fig. 20: View Of Vacuum Gauge

Courtesy of GENERAL MOTORS COMPANY

14. Continue to draw vacuum until the needle stops rising. This should be 610-660 mm Hg (24-26 in Hg).

Cooling hoses may start to collapse. This is normal due to vacuum draw.

15. To aid in the fill process, position the graduated reservoir above the coolant fill port.

Fig. 21: Identifying Valve On Vacuum Gage Assembly Courtesy of GENERAL MOTORS COMPANY

16. Slowly open the valve on the vacuum gauge assembly. When the coolant reaches the top of the fill hose, close the valve. This will eliminate air from the fill hose.

17. Close the valve on the venturi assembly.

18. If there is a suspected leak in the cooling system, allow the system to stabilize under vacuum and monitor for vacuum loss.

If vacuum loss is observed, refer to Loss of Coolant.

19. Open the valve on the vacuum gauge assembly. The vacuum gauge will drop as coolant is drawn into the system.

Fig. 22: View Of Vacuum Gauge & Radiator Courtesy of GENERAL MOTORS COMPANY

20. Once the vacuum gauge reaches zero, close the valve on the vacuum gauge.

21. Repeat steps 14-21 twice.

Fig. 23: Attaching Extraction Hose To Vacuum Hose Courtesy of GENERAL MOTORS COMPANY

22. Detach the Vac N Fill cap from the GE-42401-3 Radiator Cap and Surge Tank Test Adapter.

23. Remove GE-42401-2 Radiator Cap and Surge Tank Test Adapter from the surge tank fill neck.

24. Add coolant to the system as necessary.

25. Turn on the auxiliary coolant pump for 2 minutes using the GDS. The remote HVAC module controls the auxiliary coolant pump.

26. Start the engine.

27. Using GDS, increase the speed to 2000 rpm until the thermostat opens (approximately 100C).

NOTE: Do not allow engine coolant temperature to exceed 110C or damage to the Coolant Heater Control Module could occur.

28. Turn engine off.

29. Turn on the auxiliary coolant pump for 1 minute using GDS.

30. Turn off the auxiliary coolant pump and wait 5 minutes.

31. Repeat steps 24-30, three times.

32. Inspect the concentration of the coolant mixture using GE-26568 Coolant and Battery Tester.

NOTE: After filling the cooling system, the extraction hose can be used to remove excess coolant to achieve the proper coolant level.

33. Detach the vacuum hose form the vacuum gauge assembly.

34. Attach the extraction hose to the vacuum hose.

Fig. 24: Identifying Valve On Venturi Assembly Courtesy of GENERAL MOTORS COMPANY

35. Open the valve on the venturi assembly to start a vacuum draw.

Fig. 25: Using Extraction Hose To Draw Out Coolant Courtesy of GENERAL MOTORS COMPANY

36. Use the extraction hose to draw out coolant to the proper level.

37. The vacuum tank has a drain valve on the bottom of the tank. Open the valve to drain coolant from the vacuum tank into a suitable container for disposal.

FLUSHING

NOTE: This procedure is intended for the engine cooling system only. Never use this procedure to flush the hybrid cooling system.

When the cooling system becomes contaminated, the cooling system should be flushed thoroughly to remove the contaminants before the engine is seriously damaged.

This procedure is effective in removing contaminants caused by the use of improper coolants, coolant at the end of its life, or some liquid chemical flushing agents. This procedure is NOT effective for removing debris contamination caused by component failure, or the use of 'stop leak' additives. When the system is contaminated by this type of debris, use the

system flow diagrams to identify components that may need replacement to restore proper system flow.

Do not use chemical flush agents.

Store used coolant in the proper manner, such as in a used engine coolant holding tank. Do not pour used coolant down a drain. Ethylene glycol antifreeze is a very toxic chemical. Do not dispose of coolant into the sewer system or ground water. This is illegal and ecologically unsound.

Various methods and equipment can be used to flush the cooling system.

If special equipment is used, such as a back flusher, follow the manufacturer's instruction. Always remove the thermostat before flushing the cooling system.

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Radiator Surge Tank Replacement

3. Clean and flush the coolant recovery reservoir with clean, drinkable water.

4. Install Radiator Surge Tank Replacement

5. Follow the drain and fill procedure using only clean, drinkable water. Refer to Cooling System Draining and Filling.

6. Run the engine for 20 minutes.

7. Stop the engine.

8. Drain the cooling system. Cooling System Draining and Filling

9. Repeat the procedure if necessary, until the fluid is nearly colorless.

10. Fill the cooling system. Cooling System Draining and Filling

RADIATOR CLEANING

WARNING: NEVER spray water on a hot heat exchanger. The resulting steam could cause personal injury.

CAUTION: The heat exchanger fins are necessary for good heat transfer. Do not brush the fins. This may cause damage to the fins, reducing heat transfer.

NOTE: Remove bugs, leaves, dirt and other debris by blowing compressed air through the engine side of the radiator.

Some conditions may require the use of warm water and a mild detergent. Clean the A/C condenser fins.

Clean between the A/C condenser and radiator. Clean the radiator cooling fins.

Straighten any damaged cooling fins.

RADIATOR SURGE TANK REPLACEMENT

Special Tools

BO-38185 Hose Clamp Pliers Equivalent regional tools: Special Tools Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

Fig. 26: Coolant Hose And Wiring Harness Clip Courtesy of GENERAL MOTORS COMPANY

2. Loosen Clamp (1, 3) BO-38185 pliers

3. Remove Coolant Hose (4)

4. Unclip Wiring Harness Clip(2)

Fig. 27: Radiator Surge Tank, Bracket And Clips Courtesy of GENERAL MOTORS COMPANY

5. Remove Radiator Surge Tank Clip(1)

NOTE: To remove the radiator surge tank from the radiator surge tank bracket move it in driving direction.

6. Move the radiator surge tank (4) in arrow direction to release the radiator surge tank clip (2) from the radiator surge tank bracket (3).

Installation Procedure

Fig. 28: Radiator Surge Tank, Bracket And Clips Courtesy of GENERAL MOTORS COMPANY

NOTE: To install the radiator surge tank to the radiator surge tank bracket move it against driving direction.

1. Move the radiator surge tank (4) in arrow direction to clip in the radiator surge tank clip (2) into the radiator surge tank bracket (3).

2. Install Radiator Surge Tank Clip (1)

Fig. 29: Coolant Hose And Wiring Harness Clip Courtesy of GENERAL MOTORS COMPANY

3. Install Wiring Harness Clip (2)

4. Install Coolant Hose(4)

5. Install Clamp(1, 3) BO-38185 pliers

6. Fill the cooling system. Cooling System Draining and Filling

RADIATOR INLET HOSE REPLACEMENT

Special Tools

BO-38185 Hose Clamp Pliers Equivalent regional tools: Special Tools

Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

Fig. 30: Radiator Surge Tank Bracket Bolts Courtesy of GENERAL MOTORS COMPANY

NOTE: Do not remove any coolant hoses from the surge tanks.

2. Remove the 2 radiator surge tank bracket bolts (2).

3. To gain access to the second radiator inlet hose clamp, lay the radiator surge tank assembly (1) aside.

Fig. 31: Radiator Inlet Hose Clamp And Radiator Inlet Hose Courtesy of GENERAL MOTORS COMPANY

4. Remove Radiator Inlet Hose Clamp (1, 2) BO-38185 pliers

5. Remove Radiator Inlet Hose (3)

Installation Procedure

Fig. 32: Radiator Inlet Hose Clamp And Radiator Inlet Hose Courtesy of GENERAL MOTORS COMPANY

1. Install Radiator Inlet Hose (3)

2. Install Radiator Inlet Hose Clamp (1, 2)BO-38185 pliers

Fig. 33: Radiator Surge Tank Bracket Bolts Courtesy of GENERAL MOTORS COMPANY

3. Reposition the radiator surge tank assembly (1).

CAUTION: Fastener Caution

4. Install the 2 radiator surge tank bracket bolts (2) and tighten to 22 N.m (16 lb ft).

5. Fill the cooling system. Cooling System Draining and Filling

RADIATOR OUTLET HOSE REPLACEMENT

Fig. 34: Radiator Outlet Hose

Courtesy of GENERAL MOTORS COMPANY

RADIATOR VENT OUTLET HOSE REPLACEMENT

Fig. 35: Radiator Vent Outlet Hose

Courtesy of GENERAL MOTORS COMPANY

EXHAUST GAS RECIRCULATION COOLER WATER BYPASS OUTLET HOSE REPLACEMENT

Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Three-Way Catalytic Converter Replacement

Fig. 36: Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose Courtesy of GENERAL MOTORS COMPANY

3. Remove Clamp (4)

4. Disconnect Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose (3) @Water Pump (1)

5. Disconnect Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose (3) @Exhaust Gas Recirculation Cooler (2)

6. Remove Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose (3)

Installation Procedure

Fig. 37: Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose Courtesy of GENERAL MOTORS COMPANY

1. Install Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose (3)

2. Connect Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose (3) @Exhaust Gas Recirculation Cooler (2)

3. Connect Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose(3)@Water Pump(1)

4. Install Clamp (4)

5. Install Three-Way Catalytic Converter Replacement

6. Fill the cooling system. - Cooling System Draining and Filling

THERMOSTAT BYPASS HOSE REPLACEMENT

Special Tools

BO-38185 Hose Clamp Pliers Equivalent regional tools: Special Tools Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Heater Outlet Hose Vapor Vent Hose Replacement

3. Remove Radiator Inlet Hose@Water Outlet Radiator Inlet Hose Replacement

Fig. 38: Thermostat Bypass Hose Clamp Courtesy of GENERAL MOTORS COMPANY

4. Loosen Thermostat Bypass Hose Clamp (1) BO-38185 pliers

5. Disconnect Thermostat Bypass Hose(2)

Fig. 39: Heater Outlet Hose Clamp

Courtesy of GENERAL MOTORS COMPANY

6. Loosen Heater Outlet Hose Clamp(2) BO-38185 pliers

7. Disconnect Heater Outlet Hose (1)

Fig. 40: Engine Coolant Temperature Sensor Electrical Connector And Water Outlet Bolts Courtesy of GENERAL MOTORS COMPANY

8. Disconnect the engine coolant temperature sensor electrical connector.(1)

9. Remove the water outlet bolts.(2)

Fig. 41: Water Outlet And Gasket

Courtesy of GENERAL MOTORS COMPANY

10. Remove the water outlet.(2)

11. Remove Water Outlet Gasket (1) and DISCARD

Fig. 42: Thermostat Bypass Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

12. Remove Thermostat Bypass Hose Clamp (2) BO-38185 pliers

13. Remove Thermostat Bypass Hose(1)

Installation Procedure

Fig. 43: Thermostat Bypass Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

1. Install Thermostat Bypass Hose (1)

2. Install Thermostat Bypass Hose Clamp (2)BO-38185 pliers

Fig. 44: Water Outlet And Gasket

Courtesy of GENERAL MOTORS COMPANY

3. Install a NEW gasket to the water outlet.(1)

4. Install the water outlet.(2)

Fig. 45: Engine Coolant Temperature Sensor Electrical Connector And Water Outlet Bolts Courtesy of GENERAL MOTORS COMPANY

CAUTION: Fastener Caution

5. Install Water Outlet Bolt (2) and tighten 12 N.m (106 lb in)

6. Connect the engine coolant temperature sensor electrical connector.(1)

Fig. 46: Heater Outlet Hose Clamp

Courtesy of GENERAL MOTORS COMPANY

7. Install Heater Outlet Hose (1)

8. Install Heater Outlet Hose Clamp (2) BO-38185 pliers

Fig. 47: Thermostat Bypass Hose Clamp Courtesy of GENERAL MOTORS COMPANY

9. Install Thermostat Bypass Hose (2)

10. Install Thermostat Bypass Hose Clamp (1) BO-38185 pliers

11. Install Radiator Inlet Hose@Water Outlet Radiator Inlet Hose Replacement

12. Install Heater Outlet Hose Vapor Vent Hose Replacement

13. Fill the cooling system. Cooling System Draining and Filling

WATER PUMP INLET ADAPTER REPLACEMENT

Fig. 48: Water Pump Inlet Adapter

Courtesy of GENERAL MOTORS COMPANY

ENGINE COOLANT THERMOSTAT HOUSING REPLACEMENT

Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Radiator Outlet Hose@Engine Coolant Thermostat Housing Radiator Outlet Hose Replacement

Fig. 49: Electrical Connector And Engine Coolant Thermostat Housing Bolt Courtesy of GENERAL MOTORS COMPANY

3. Disconnect Electrical Connector (2) @Engine Coolant Thermostat Housing (4)

4. Remove Engine Coolant Thermostat Housing Bolt (1)

5. Remove Engine Coolant Thermostat Housing (4)

6. Remove Engine Coolant Thermostat Gasket (3) and DISCARD

Installation Procedure

Fig. 50: Electrical Connector And Engine Coolant Thermostat Housing Bolt Courtesy of GENERAL MOTORS COMPANY

1. Install a NEW gasket.(3)

2. Install Engine Coolant Thermostat Housing (4)

CAUTION: Fastener Caution

3. Install Engine Coolant Thermostat Housing Bolt (1) and tighten 10 N.m (89 lb in)

4. Connect Electrical Connector(2)@Engine Coolant Thermostat Housing(4)

5. Radiator Outlet Hose@Engine Coolant Thermostat Housing Radiator Outlet Hose Replacement

6. Fill the cooling system. Cooling System Draining and Filling

WATER OUTLET REPLACEMENT

Special Tools

BO-38185 Hose Clamp Pliers Equivalent regional tools: Special Tools Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Heater Outlet Hose Vapor Vent Hose Replacement

3. Remove Radiator Inlet Hose@Water Outlet Radiator Inlet Hose Replacement

Fig. 51: Thermostat Bypass Hose Clamp Courtesy of GENERAL MOTORS COMPANY

4. Loosen Thermostat Bypass Hose Clamp (1) BO-38185 pliers

5. Disconnect Thermostat Bypass Hose (2)

Fig. 52: Heater Outlet Hose Clamp

Courtesy of GENERAL MOTORS COMPANY

6. Loosen Heater Outlet Hose Clamp (2)BO-38185 pliers

7. Disconnect Heater Outlet Hose (1)

Fig. 53: Engine Coolant Temperature Sensor Electrical Connector And Water Outlet Bolts Courtesy of GENERAL MOTORS COMPANY

8. Disconnect the engine coolant temperature sensor electrical connector.(1)

9. Remove the water outlet bolts.(2)

Fig. 54: Water Outlet And Gasket

Courtesy of GENERAL MOTORS COMPANY

10. Remove the water outlet.(2)

11. Remove Water Outlet Gasket (1) and DISCARD

Fig. 55: Thermostat Bypass Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

12. Remove Thermostat Bypass Hose Clamp (4) BO-38185 pliers

13. Remove Thermostat Bypass Hose (1)

14. Remove Engine Coolant Temperature Sensor Retainer(2)

15. Remove the engine coolant temperature sensor.(3)

Installation Procedure

Fig. 56: Thermostat Bypass Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

1. Install the engine coolant temperature sensor.(3)

2. Install Engine Coolant Temperature Sensor Retainer(2)

3. Install Thermostat Bypass Hose (1)

4. Install Thermostat Bypass Hose Clamp (4)BO-38185 pliers

Fig. 57: Water Outlet And Gasket

Courtesy of GENERAL MOTORS COMPANY

5. Install a NEW gasket to the water outlet.(1)

6. Install the water outlet.(2)

Fig. 58: Engine Coolant Temperature Sensor Electrical Connector And Water Outlet Bolts Courtesy of GENERAL MOTORS COMPANY

CAUTION: Fastener Caution

7. Install Water Outlet Bolt (2) and tighten 12 N.m (106 lb in)

8. Connect the engine coolant temperature sensor electrical connector.(1)

Fig. 59: Heater Outlet Hose Clamp

Courtesy of GENERAL MOTORS COMPANY

9. Install Heater Outlet Hose (1)

10. Install Heater Outlet Hose Clamp (2) BO-38185 pliers

Fig. 60: Thermostat Bypass Hose Clamp Courtesy of GENERAL MOTORS COMPANY

11. Install Thermostat Bypass Hose (2)

12. Install Thermostat Bypass Hose Clamp (1)BO-38185 pliers

13. Install Radiator Inlet Hose@Water Outlet Radiator Inlet Hose Replacement

14. Install Heater Outlet Hose Vapor Vent Hose Replacement

15. Fill the cooling system. Cooling System Draining and Filling

WATER PUMP BELT REPLACEMENT

Removal Procedure

1. Remove Front Compartment Air Deflector Replacement

2. Remove Front Wheelhouse Liner Replacement (Left Side) Front Wheelhouse Liner Replacement (Right Side) - Right Side

3. Remove Heater Inlet Hose@Heater Coolant Heater Heater Inlet Hose Replacement

4. Remove Heater Inlet and Outlet Pipe@Heater Coolant Heater Heater Inlet And Outlet Pipe Replacement

Fig. 61: Water Pump Belt

Courtesy of GENERAL MOTORS COMPANY

5. Cut the water pump belt (2) with a appropriate cutting tool at position (1).

6. Remove Water Pump Belt (2) and DISCARD

Installation Procedure

Fig. 62: Water Pump Belt

Courtesy of GENERAL MOTORS COMPANY

1. Position a NEW water pump belt (3) on the water pump pulley (2) and partially install it on the crankshaft balancer (1) in preparation to walk the belt on the crankshaft pulley.

2. Rotate the crankshaft on the crankshaft balancer bolt (4) slowly clockwise until the belt is fully installed on the crankshaft balancer (1).

3. After the belt is on the crankshaft balancer, rotate the crankshaft an additional complete revolution and ensure the water pump belt is fully seated on the crankshaft balancer and water pump pulley.

4. Install Heater Inlet and Outlet Pipe@Heater Coolant Heater Heater Inlet And Outlet Pipe Replacement

5. Install Heater Inlet Hose@Heater Coolant Heater Heater Inlet Hose Replacement

6. Install Front Wheelhouse Liner Replacement (Left Side) Front Wheelhouse Liner Replacement (Right Side) - Right Side

7. Install Front Compartment Air Deflector Replacement

WATER PUMP REPLACEMENT

Removal Procedure

1. Remove Water Pump Belt Replacement

2. Remove Exhaust Gas Recirculation Cooler Replacement

3. Remove Water Pump Inlet Adapter Replacement

4. Remove Radiator Outlet Hose Replacement

5. Disconnect Electrical Connector@Heated Oxygen Sensor Heated Oxygen Sensor Replacement - Sensor 1

Fig. 63: Electrical Connector And Retainer Courtesy of GENERAL MOTORS COMPANY

6. Remove Retainer (1)

7. Disconnect Electrical Connector (2) @Engine Coolant Thermostat Housing

Fig. 64: Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose And Water Pump Courtesy of GENERAL MOTORS COMPANY

8. Remove Clamp (5)

9. Remove the exhaust gas recirculation cooler water bypass outlet hose (6) from the water pump (1).

NOTE: Take note that there are different bolt lengths.

10. Remove Water Pump Bolt (2, 8)

11. Remove the 3 bolt retainers (3, 7).

12. Remove Water Pump (1)

13. Remove Water Pump Gasket (4) and DISCARD

Installation Procedure

Fig. 65: Exhaust Gas Recirculation Cooler Water Bypass Outlet Hose And Water Pump Courtesy of GENERAL MOTORS COMPANY

1. Install a NEW gasket.(4)

2. Install Water Pump (1)

NOTE: Take note that there are different bolt lengths.

3. Install Water Pump Bolt(2, 8)

CAUTION: Fastener Caution

4. Tighten the NEW water pump bolts.25 N.m (18 lb ft)

5. Install the exhaust gas recirculation cooler water bypass outlet hose (6) to the water pump (1).

6. Install Clamp (5)

Fig. 66: Electrical Connector And Retainer Courtesy of GENERAL MOTORS COMPANY

7. Install Retainer(1)

8. Connect Electrical Connector (2) @Engine Coolant Thermostat Housing

9. Connect Electrical Connector@Heated Oxygen Sensor Heated Oxygen Sensor Replacement - Sensor 1

10. Install Exhaust Gas Recirculation Cooler Replacement

11. Install Water Pump Inlet Adapter Replacement

12. Install Radiator Outlet Hose Replacement

13. Install Water Pump Belt Replacement

WATER PUMP HOUSING REPLACEMENT

Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Water Pump Belt Replacement

Fig. 67: Water Pump Housing And Water Pump Bolt Courtesy of GENERAL MOTORS COMPANY

3. Remove Water Pump Bolt (1)

4. Remove Water Pump Housing (2)

5. Remove Water Pump Housing Gasket (3) and DISCARD

6. Remove the old gasket material from the water pump sealing surfaces.

Installation Procedure

Fig. 68: Water Pump Housing And Water Pump Bolt Courtesy of GENERAL MOTORS COMPANY

1. Install a New Water Pump Housing Gasket (3).

2. Install Water Pump Housing (2)

CAUTION: Fastener Caution

3. Install Water Pump Bolt (1) and tighten 10 N.m (89 lb in)

4. Install Water Pump Belt Replacement

5. Fill the cooling system. Cooling System Draining and Filling

ENGINE COOLANT TEMPERATURE SENSOR REPLACEMENT - RADIATOR

Fig. 69: Engine Coolant Temperature Sensor Courtesy of GENERAL MOTORS COMPANY

RADIATOR DRAIN COCK REPLACEMENT

Fig. 70: Radiator Drain Cock

Courtesy of GENERAL MOTORS COMPANY

ENGINE COOLANT FAN SHROUD REPLACEMENT

Special Tools

BO-38185 Hose Clamp Pliers Equivalent regional tools: Special Tools Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling

2. Remove Hood Primary and Secondary Latch Replacement

3. Remove Front Intake Air Duct Replacement

4. Remove Transmission Fluid Auxiliary Cooler Replacement

5. Remove Radiator Inlet Hose@Radiator Radiator Inlet Hose Replacement

6. Remove Radiator Outlet Hose@Radiator Radiator Outlet Hose Replacement

Fig. 71: Ground Cable Nut And Ground Cable Courtesy of GENERAL MOTORS COMPANY

7. Remove Ground Cable Nut (2)

8. Remove Ground Cable (1)

9. Unclip Wiring Harness Clip (3)

Fig. 72: Electrical Connector And Cable Tie Courtesy of GENERAL MOTORS COMPANY

10. Disconnect the electrical connector.(1, 3, 4)

11. Remove Cable Tie (2)

Fig. 73: Heat Shield

Courtesy of GENERAL MOTORS COMPANY

12. Remove Heat Shield Nut (2)

13. Remove Heat Shield (1)

Fig. 74: Drive Motor Battery Coolant Pump Bracket Studs Courtesy of GENERAL MOTORS COMPANY

NOTE: Mind the position of the pump and the bracket.

14. Remove the 2 drive motor battery coolant pump bracket studs (1).

NOTE: It is not necessary to remove any coolant hoses from the drive motor battery coolant pump.

15. Remove the drive motor battery coolant pump (3) and hang aside.

16. Remove the 2 drive motor battery coolant pump brackets (2, 4).

Fig. 75: Radiator Upper Insulator And Bolt Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator upper insulator right side. Procedure is also valid for the left side.

17. Remove the radiator upper insulator bolt (1).

18. Remove the radiator upper insulator (2) by rotating in arrow direction.

19. Repeat the procedure for the other side.

Fig. 76: Radiator Vent Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

20. Remove Clamp (1)- BO-38185 pliers

21. Remove the radiator vent hose (2) from the radiator.

Fig. 77: Radiator And Radiator Insulators Courtesy of GENERAL MOTORS COMPANY

22. Remove the radiator (1) along with the fan shroud carefully in top direction from the radiator support brackets.

23. Remove the 2 radiator insulators (2).

Fig. 78: Wiring Harness Clip And Engine Coolant Fan Shroud Bolt Courtesy of GENERAL MOTORS COMPANY

24. Unclip Wiring Harness Clip (2, 5)

25. Remove Engine Coolant Fan Shroud Bolt (1, 3)

26. Unclip Retainer(4)

27. Remove Engine Coolant Fan Shroud (6) @Radiator

Fig. 79: Wiring Harness Clip And Electrical Connector Courtesy of GENERAL MOTORS COMPANY

28. Disconnect the electrical connector.(2, 4)

29. Unclip Wiring Harness Clip (1, 3, 5)

30. Remove Wiring Harness (6) @Engine Coolant Fan Shroud

Installation Procedure

Fig. 80: Wiring Harness Clip And Electrical Connector Courtesy of GENERAL MOTORS COMPANY

1. Install Wiring Harness (6) @Engine Coolant Fan Shroud

2. Install Wiring Harness Clip (1, 3, 5)

3. Connect the electrical connector.(2, 4)

Fig. 81: Wiring Harness Clip And Engine Coolant Fan Shroud Bolt Courtesy of GENERAL MOTORS COMPANY

4. Install Engine Coolant Fan Shroud (6) @Radiator

5. Install Retainer(4)

CAUTION: Fastener Caution

6. Install Engine Coolant Fan Shroud Bolt (1, 3) and tighten 5 N.m (44 lb in)

7. Install Wiring Harness Clip

Fig. 82: Radiator And Radiator Insulators Courtesy of GENERAL MOTORS COMPANY

8. Install the 2 radiator insulators (2).

9. Install the radiator (1) along with the fan shroud carefully to the radiator support brackets.

Fig. 83: Radiator Upper Insulator And Bolt Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator upper insulator right side. Procedure is also valid for the left side.

10. Install the radiator upper insulator (2) by rotating against arrow direction.

11. Install the radiator upper insulator bolt (1) and tighten to 22 N.m (16 lb ft).

12. Repeat the procedure for the other side.

Fig. 84: Radiator Vent Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

13. Install the radiator vent hose (2) to the radiator.

14. Install Clamp (1) BO-38185 pliers

Fig. 85: Drive Motor Battery Coolant Pump Bracket Studs Courtesy of GENERAL MOTORS COMPANY

15. Install the drive motor battery coolant pump bracket (4).

16. Install the drive motor battery coolant pump (3).

NOTE: Check the pump and the bracket for the correct original position.

17. Install the drive motor battery coolant pump bracket (2).

18. Install the 2 drive motor battery coolant pump bracket studs (1) and tighten to 9 N.m (80 lb in).

Fig. 86: Heat Shield

Courtesy of GENERAL MOTORS COMPANY

19. Install Heat Shield (1)

20. Install Heat Shield Nut (2) and tighten 9 N.m (80 lb in)

Fig. 87: Electrical Connector And Cable Tie Courtesy of GENERAL MOTORS COMPANY

21. Connect the electrical connector.(1, 3, 4)

22. Install NEW cable ties.(2)

Fig. 88: Ground Cable Nut And Ground Cable Courtesy of GENERAL MOTORS COMPANY

23. Install Ground Cable (1)

24. Install Ground Cable Nut (2) and tighten 9 N.m (80 lb in)

25. Install Wiring Harness Clip (3)

26. Install Radiator Outlet Hose@Radiator Radiator Outlet Hose Replacement

27. Install Radiator Inlet Hose@Radiator Radiator Inlet Hose Replacement

28. Install Transmission Fluid Auxiliary Cooler Replacement

29. Install Hood Primary and Secondary Latch Replacement

30. Install Front Intake Air Duct Replacement

31. Fill the cooling system. Cooling System Draining and Filling

RADIATOR REPLACEMENT

Special Tools

BO-38185 Hose Clamp Pliers Equivalent regional tools: Special Tools Removal Procedure

1. Drain the cooling system. Cooling System Draining and Filling.

2. Remove Hood Primary and Secondary Latch Replacement

3. Remove Front Intake Air Duct Replacement

4. Remove Transmission Fluid Auxiliary Cooler Replacement

5. Remove Radiator Inlet Hose@Radiator Radiator Inlet Hose Replacement

6. Remove Radiator Outlet Hose@Radiator Radiator Outlet Hose Replacement

Fig. 89: Ground Cable Nut And Ground Cable Courtesy of GENERAL MOTORS COMPANY

7. Remove Ground Cable Nut (2)

8. Remove Ground Cable (1)

9. Unclip Wiring Harness Clip (3)

Fig. 90: Electrical Connector And Cable Tie Courtesy of GENERAL MOTORS COMPANY

10. Disconnect the electrical connector.(1, 3, 4)

11. Remove Cable Tie (2)

Fig. 91: Heat Shield

Courtesy of GENERAL MOTORS COMPANY

12. Remove Heat Shield Nut (2)

13. Remove Heat Shield (1)

Fig. 92: Drive Motor Battery Coolant Pump Bracket Studs Courtesy of GENERAL MOTORS COMPANY

NOTE: Mind the position of the pump and the bracket.

14. Remove the 2 drive motor battery coolant pump bracket studs (1).

NOTE: It is not necessary to remove any coolant hoses from the drive motor battery coolant pump.

15. Remove the drive motor battery coolant pump (3) and hang aside.

16. Remove the 2 drive motor battery coolant pump brackets (2, 4).

Fig. 93: Radiator Upper Insulator And Bolt Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator upper insulator right side. Procedure is also valid for the left side.

17. Remove the radiator upper insulator bolt (1).

18. Remove the radiator upper insulator (2) by rotating in arrow direction.

19. Repeat the procedure for the other side.

Fig. 94: Radiator Vent Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

20. Remove Clamp (1) BO-38185 pliers

21. Remove the radiator vent hose (2) from the radiator.

Fig. 95: Radiator And Radiator Insulators Courtesy of GENERAL MOTORS COMPANY

22. Remove the radiator (1) along with the fan shroud carefully in top direction from the radiator support brackets.

23. Remove the 2 radiator insulators (2).

Fig. 96: Wiring Harness Clip And Engine Coolant Fan Shroud Bolt Courtesy of GENERAL MOTORS COMPANY

24. Unclip Wiring Harness Clip (2, 5)

25. Remove Engine Coolant Fan Shroud Bolt (1, 3)

26. Unclip Retainer(4)

27. Remove Engine Coolant Fan Shroud (6) @Radiator

Disassemble Procedure

1. Remove Engine Coolant Temperature Sensor Replacement - Radiator

2. Remove Radiator Drain Cock Replacement

Assemble Procedure

1. Install Radiator Drain Cock Replacement

2. Install Engine Coolant Temperature Sensor Replacement - Radiator

Installation Procedure

Fig. 97: Wiring Harness Clip And Engine Coolant Fan Shroud Bolt Courtesy of GENERAL MOTORS COMPANY

1. Install Engine Coolant Fan Shroud (6) @Radiator

2. Install Retainer(4)

CAUTION: Fastener Caution

3. Install Engine Coolant Fan Shroud Bolt (1, 3) and tighten 5 N.m (44 lb in)

4. Install Wiring Harness Clip

Fig. 98: Radiator And Radiator Insulators Courtesy of GENERAL MOTORS COMPANY

5. Install the 2 radiator insulators (2).

6. Install the radiator (1) along with the fan shroud carefully to the radiator support brackets.

Fig. 99: Radiator Upper Insulator And Bolt Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator upper insulator right side. Procedure is also valid for the left side.

7. Install the radiator upper insulator (2) by rotating against arrow direction.

8. Install the radiator upper insulator bolt (1) and tighten to 22 N.m (16 lb ft).

9. Repeat the procedure for the other side.

Fig. 100: Radiator Vent Hose And Clamp Courtesy of GENERAL MOTORS COMPANY

10. Install the radiator vent hose (2) to the radiator.

11. Install Clamp (1) BO-38185 pliers

Fig. 101: Drive Motor Battery Coolant Pump Bracket Studs Courtesy of GENERAL MOTORS COMPANY

12. Install the drive motor battery coolant pump bracket (4).

13. Install the drive motor battery coolant pump (3).

NOTE: Check the pump and the bracket for the correct original position.

14. Install the drive motor battery coolant pump bracket (2).

15. Install the 2 drive motor battery coolant pump bracket studs (1) and tighten to 9 N.m (80 lb in).

Fig. 102: Heat Shield

Courtesy of GENERAL MOTORS COMPANY

16. Install Heat Shield (1)

17. Install Heat Shield Nut (2) and tighten 9 N.m (80 lb in)

Fig. 103: Electrical Connector And Cable Tie Courtesy of GENERAL MOTORS COMPANY

18. Connect the electrical connector.(1, 3, 4)

19. Install NEW cable ties.(2)

Fig. 104: Ground Cable Nut And Ground Cable Courtesy of GENERAL MOTORS COMPANY

20. Install Ground Cable (1)

21. Install Ground Cable Nut (2) and tighten 9 N.m (80 lb in)

22. Install Wiring Harness Clip (3)

23. Install Radiator Outlet Hose@Radiator Radiator Outlet Hose Replacement

24. Install Radiator Inlet Hose@Radiator Radiator Inlet Hose Replacement

25. Install Transmission Fluid Auxiliary Cooler Replacement

26. Hood Primary and Secondary Latch Replacement

27. Front Intake Air Duct Replacement

28. Fill the cooling system. Cooling System Draining and Filling

RADIATOR UPPER INSULATOR REPLACEMENT

Removal Procedure

1. Remove Front Intake Air Duct Replacement

Fig. 105: Radiator Upper Insulator And Bolt Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator upper insulator right side. Procedure is also valid for the left side.

2. Remove Radiator Upper Insulator Bolt (1)

3. Remove the radiator upper insulator (2) by rotating in arrow direction.

Installation Procedure

Fig. 106: Radiator Upper Insulator And Bolt Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator upper insulator right side. Procedure is also valid for the left side.

1. Install the radiator upper insulator (2) by rotating it against arrow direction.

CAUTION: Fastener Caution

2. Install Radiator Upper Insulator Bolt (1) and tighten 22 N.m (16 lb ft)

3. Install Front Intake Air Duct Replacement

RADIATOR AIR LOWER BAFFLE AND DEFLECTOR REPLACEMENT

Removal Procedure

1. Remove Front Bumper Fascia Removal and Installation

2. Remove Front Bumper Shutter Replacement

Fig. 107: Wiring Harness Clip

Courtesy of GENERAL MOTORS COMPANY

3. Unclip Wiring Harness Clip (1)

Fig. 108: Clip

Courtesy of GENERAL MOTORS COMPANY

4. Unclip Clip (1, 2)

Fig. 109: Radiator Air Lower Baffle Bolt Courtesy of GENERAL MOTORS COMPANY

5. Remove the 4 radiator air lower baffle bolts (1, 2).

6. Remove Radiator Air Lower Baffle (3)

Installation Procedure

Fig. 110: Radiator Air Lower Baffle Bolt Courtesy of GENERAL MOTORS COMPANY

CAUTION: Fastener Caution

1. Install Radiator Air Lower Baffle (3)

Install the 4 radiator air lower baffle bolts (1, 2) and tighten to 9 N.m (80 lb in).

Fig. 111: Clip

Courtesy of GENERAL MOTORS COMPANY

2. Install Clip (1, 2)

Fig. 112: Wiring Harness Clip

Courtesy of GENERAL MOTORS COMPANY

3. Install Wiring Harness Clip (1)

4. Install Front Bumper Shutter Replacement

5. Install Front Bumper Fascia Removal and Installation

RADIATOR AIR UPPER BAFFLE AND DEFLECTOR REPLACEMENT

Removal Procedure

1. Remove Front Intake Air Duct Replacement

2. Remove Pedestrian Sound Alert Speaker Replacement

Fig. 113: Clip

Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator air upper baffle and deflector right side.

Procedure is also valid for the left side.

3. Unclip Clip (1)

4. Repeat the procedure for the other side.

Fig. 114: Clip

Courtesy of GENERAL MOTORS COMPANY

NOTE: Mind the different clip size.

5. Unclip Clip (1)

6. Remove Radiator Air Upper Baffle and Deflector (2)

Installation Procedure

Fig. 115: Clip

Courtesy of GENERAL MOTORS COMPANY

1. Install Radiator Air Upper Baffle and Deflector (2)

NOTE: Mind the different clip size.

2. Install Clip (1)

Fig. 116: Clip

Courtesy of GENERAL MOTORS COMPANY

NOTE: Graphic shows the radiator air upper baffle and deflector right side.

Procedure is also valid for the left side.

3. Install Clip (1)

4. Repeat the procedure for the other side.

5. Install Pedestrian Sound Alert Speaker Replacement

6. Install Front Intake Air Duct Replacement DESCRIPTION AND OPERATION COOLING FAN DESCRIPTION AND OPERATION

Cooling Fan Control

The engine cooling fan(s) system is composed of 2 electric cooling fan(s), 2 fan motor(s) and 2 control module. The Hybrid/EV Powertrain Control Module 2 controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module(s). The cooling fan control module(s) varies the voltage drop across the cooling fan motor(s) in relation to the pulse width modulated signal, which allows the cooling fan(s) to operate at variable speeds.

The cooling fan speed is effected by many different conditions and the Hybrid/EV Powertrain Control Module 2 will adjust the duty cycle from 0 - 100 percent based on cooling system requirements. The scan tool output control is only capable of operating the cooling fan(s) increments, between 10 - 90 percent. 90 percent is considered high speed fan. When multiple cooling fan speed requests are received, the Hybrid/EV Powertrain

Control Module 2 operates the fan(s) at the highest of speed requests. The ECM commands the fans ON under the following conditions:

The engine coolant temperature is warmer than a predetermined temperature. The engine oil temperature is warmer than a predetermined temperature.

The A/C pressure reaches a predetermined pressure.

If the engine coolant temperature at key-off is warmer than a predetermined value, or the A/C pressure is greater than a predetermined value, the cooling fan(s) will operate at a low speed. The fan(s) will shut OFF if the temperature or pressure drops below the predetermined value, but will only operate for 2 minutes, regardless of the coolant temperature or A/C pressure.

Cooling System Electronic Component Description and Operation

Engine or Radiator Coolant Temperature Sensor

The engine coolant temperature (ECT) sensor or radiator coolant temperature (RCT) sensor is a variable resistor that measures the temperature of the engine or radiator coolant. The ECM supplies 5 V to the sensor signal circuit and a ground for the low reference circuit.

Engine Coolant Thermostat Heater

The ECM controls the pulse width modulated (PWM) thermostat heater circuit. The engine coolant thermostat heater helps control coolant flow and regulates the engine operating temperature. The ignition relay supplies 12 V to the thermostat through a fuse. The ECM controls the engine coolant thermostat heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

COOLING SYSTEM DESCRIPTION AND OPERATION

This vehicle is equipped with three fully independent cooling systems. The power electronics cooling system is dedicated to cooling the battery charger and the power inverter module. The battery cooling system is dedicated to cooling and heating the high voltage battery. The engine cooling system is dedicated to cooling the engine and providing heat to the passenger compartment.

Engine Cooling System Description and Operation

The engine cooling system consists of a radiator, two 12 volt pulse width modulated (PWM) radiator fans, a 12 volt coolant pump, a coolant flow control valve, a high voltage heater and a heater core.

Fig. 117: Hybrid Cooling System Chart Courtesy of GENERAL MOTORS COMPANY

The hybrid/EV powertrain control module 2 controls the radiator cooling fans. The cooling fans are controlled with a Pulse Width Modulated (PWM) signal. The hybrid/EV powertrain control module 2 diagnoses any faults with the hardwire circuit to the engine control module. The engine control module sends a fan request PWM signal to the hybrid/EV powertrain control module 2 through a hardwire circuit. The hybrid/EV powertrain control module 2 operates in a pass-through mode for the engine control module fan request. The higher the duty cycle the higher the cooling fan speed.

The hybrid/EV powertrain control module 2 sends a request to the engine control module for the cooling fans to be turned on. The engine control module uses this request and other vehicle inputs to decide if and what speed the cooling fans should operate. The engine control module sends the cooling fan command to the hybrid/EV powertrain control module 2. The hybrid/EV powertrain control module 2 sends the signal to the cooling fans to operate and at what speed.

If the vehicle is in Charge Mode and the hybrid/EV powertrain control module 2 requests the cooling fans to operate, if the engine control module is not awake, the hybrid/EV powertrain control module 2 will control the cooling fans. If active cooling is needed, the engine control module wakes up to operate the air conditioning control module and then the engine control module is the master controller for the fans.

Fig. 118: Engine Cooling System Flow Chart Courtesy of GENERAL MOTORS COMPANY

The HVAC Control Module turns on the coolant pump and monitors the temperature sensors in the passenger compartment, engine radiator, high voltage heater and the engine to determine the position of the coolant flow control valve and if the high voltage heater is needed. Passenger compartment heat is provided by air flowing through the heater core. The heater core is heated by coolant from either the engine or the high voltage heater.

The engine cooling system circulates a 50/50 mixture of DEX-COOL and distilled water.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

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