Engine Cooling System: Diagnosis GMC Terrain I

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Conditions for Running the DTC

1. The ignition voltage is greater than 11 volts.
2. The ECM driver transitions from ON to OFF or from OFF to ON.
3. DTCs P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

Conditions for Setting the DTC

The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.

Action Taken When the DTC Sets

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

Diagnostic Aids

1. The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
2. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relay 2 and 3 operates 1 fan at a high speed Cooling Fan Relay 1, 2 and 3 operates both fans at a high speed

Circuit/System Testing

1. Ignition OFF, disconnect all of the KR20 cooling fan relays.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below: KR20C cooling fan low speed relay terminal 86 KR20D cooling fan high speed relay terminal 86 KR20E cooling fan speed control relay terminal 85 If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
3. Connect the red lead of the DMM to a control circuit terminal listed below. Connect the black lead to ground. Set the DMM on the diode setting. The DMM should display OL. KR20C cooling fan low speed relay terminal 85 KR20D cooling fan high speed relay terminal 85 KR20E cooling fan speed control relay terminal 86 If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
4. Command the cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the K20 engine control module.
5. If all circuits test normal, test or replace the appropriate KR20 relay.

Component Testing

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL. 30 and 86 30 and 87 30 and 85 85 and 87 If less than the specified range, replace the KR20 cooling fan relay.
4. Test the KR20E cooling fan speed control relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the KR20E cooling fan speed control relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

1. The ignition voltage is greater than 11 volts.
2. The ECM driver transitions from ON to OFF or from OFF to ON.
3. DTC P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

1. The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
2. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates the fan at low speed Cooling Fan Relay 2 operates the fan at a high speed
3. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

1. Ignition OFF, disconnect both of the KR20 cooling fan relays.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below: KR20C cooling fan low speed relay terminal 86 KR20D cooling fan high speed relay terminal 86 If the test lamp does not illuminate, test the relay coil ignition circuit for or an open/high resistance.
3. Connect the red lead of the DMM to a control circuit terminal listed below. Connect the black lead to ground. Set the DMM on the diode setting. The DMM should display OL: KR20C cooling fan low speed relay terminal 85 KR20D cooling fan high speed relay terminal 85 If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.
4. Command the cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the K20 engine control module.
5. If all circuits test normal, test or replace the appropriate KR20 relay.

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL: 30 and 86 30 and 87 30 and 85 85 and 87 If less than the specified range, replace the KR20 cooling fan relay.
4. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

1. The engine is operating for greater than 30 seconds.
2. DTC P1258 runs continuously once the conditions above have been met.

The ECM detects that engine coolant temperature is warmer than 131°C (268°F) for greater than 2 seconds.

1. DTC P1258 is a Type A DTC.
2. The engine will operate in the Overheated Engine Protection Operating Mode.
3. The IP will illuminate the coolant temperature indicator lamp and the driver information center (DIC), if equipped, may display a message.
4. If the protection mode is active and an ECT sensor DTC sets, the protection mode will remain active at the start of the next drive cycle until the ECT sensor DTC runs and passes.

DTC P1258 is a Type A DTC.

1. Test the thermostat for correct operation. Refer to «Thermostat Diagnosis»(ref-491221-S36266832112012073000000) .
2. Test the engine cooling system for overheating. Refer to «Engine Overheating»(ref-491221-S10435903132012073000000) .
3. Inspect the water pump and coolant flow for correct operation. Refer to «Water Pump Cleaning and Inspection»(ref-491235-S25419550142012073000000) .
4. Inspect the engine mechanical for worn, leaking, cracked cylinder heads or engine block. Refer to «Coolant in Engine Oil»(ref-491222-S21740266022012073000000) .

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following

1. Perform «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) and verify all of the following items: Engine control module (ECM) and indicator lamp are operating correctly. There are no diagnostic trouble codes (DTCs) stored. Scan tool data is within a normal operating range.
2. Verify the customer concern.
3. 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.
4. 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 Fan Description and Operation (3.0L) , Cooling Fan Description and Operation (2.4L) , and Cooling System Description and Operation .

Visual/Physical Inspection

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

1. Ensure that the control module grounds are clean, tight, and correctly located.
2. Inspect cooling system hoses and pipes for splits, kinks, and improper connections. Inspect thoroughly for any type of leak or restriction.
3. Inspect for a dirty or restricted radiator or HVAC condenser.
4. Inspect for aftermarket devices which could affect the operation of the cooling system.
5. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
6. Inspect the surge tank reservoir for proper coolant level.

Symptom List

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

1. «Cooling Fan Always On (LEA)»(ref-491221-S06164487802012073000000) , «Cooling Fan Always On (LFW)»(ref-491221-S20842296122012073000000)
2. «Cooling Fan Inoperative (LEA)»(ref-491221-S32168532422012073000000) , «Cooling Fan Inoperative (LFW)»(ref-491221-S13580085482012073000000)
3. «Engine Overheating»(ref-491221-S10435903132012073000000)
4. «Loss of Coolant»(ref-491221-S42581165502012073000000)
5. «Thermostat Diagnosis»(ref-491221-S36266832112012073000000)
6. «Engine Fails To Reach Normal Operating Temperature»(ref-491221-S19081402882012073000000)

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates the fan at a low speed Cooling Fan Relay 2 operates the fan at a high speed
2. Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. If this condition is suspected, refer to the temperature versus resistance tables listed below. «Temperature Versus Resistance (Engine Coolant Temperature Sensor)»(ref-491226-S30242040222012073000000) «Temperature Versus Resistance - Intake Air Temperature Sensor (Hitatchi Sensor)»(ref-491226-S10570010602012073000000)

1. Ignition OFF, disconnect the KR20 Cooling Fan Relays one at a time.
2. Ignition ON, observe that the cooling fan is not activated. If the fan is activated, test for a short to voltage in the relay controlled output circuits of the engine cooling fan. If the fan is not activated, test or replace the appropriate KR20 Cooling Fan Relay.

1. Ignition OFF, disconnect the KR20 Cooling Fan Relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 Cooling Fan Relay.
3. Test for infinite resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the KR20 cooling fan relay.
4. Install a 20 A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 Cooling Fan Relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relay 2 and 3 operates the 1 fan at a high speed Cooling Fan Relay 1, 2 and 3 operates both fans at a high speed
2. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

1. Ignition OFF, disconnect each KR20 cooling fan relay one at a time.
2. Ignition ON, observe that the cooling fans are not activated. If the fans are activated, test for a short to voltage in the relay controlled output circuit of the appropriate cooling fan. If the fans are not activated, test or replace the appropriate KR20 cooling fan relay.

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL. 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the KR20 cooling fan relay.
4. Test the KR20E relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the KR20E cooling fan relay.
5. Install a 20 A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 cooling fan relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates the fan at a low speed Cooling Fan Relay 2 the fan at a high speed
2. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

1. Ignition OFF, disconnect the G10 cooling fan harness connector.
2. Disconnect the R10 cooling fan resistor harness connector.
3. Test for less than 1.0 ohms between the G10 cooling fan ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
4. Ignition ON, connect a test lamp between ground and the G10 cooling fan circuit terminal 1. Command the cooling fan ON at high speed with a scan tool. The test lamp should illuminate as commanded. If the test lamp does not illuminate, test the high speed relay controlled output circuit and B+ supply circuit for a short to ground or for an open/high resistance. If the circuits test normal and the B+ fuse is open, test or replace the G10 cooling fan motor. If the circuits and B+ fuse test normal, test or replace the KR20D fan relay.
5. Connect a test lamp between the R10 fan resistor circuit terminal 1 and ground. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate. If the test lamp does not illuminate, test the low speed relay controlled output circuit and B+ supply circuit for a short to ground or for an open/high resistance. If the circuits test normal and the B+ fuse is OK, test or replace the KR20C fan relay. If necessary, replace the B+ fuse.
6. Ignition OFF, connect the R10 fan resistor harness connector.
7. Ignition ON, connect a test lamp between ground and the G10 cooling fan circuit terminal 1. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate as commanded. If the test lamp does not illuminate, test the low speed relay controlled output circuit for a short to ground or an open/high resistance between R10 resistor terminal 2 and the J110 splice. If the circuit tests normal, test or replace the R10 cooling fan resistor.
8. If all of the circuits and components test normal, test or replace the G10 cooling fan motor.

KR20 Cooling Fan Relay

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL. 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the relay.
4. Install a 20 A fused jumper wire between relay terminal 86 and B+. Install a jumper wire between relay terminal 85 and ground. Test for less than 2ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

G10 Engine Cooling Fan

1. Ignition OFF, disconnect the harness connector at the G10 engine cooling fan.
2. Connect a jumper wire between ground and the G10 ground circuit terminal 2.
3. Connect a 30 A fused jumper wire between B+ and the G10 B+ supply circuit terminal 1. The cooling fan should operate at a High speed. If the cooling fan does not operate, replace the G10 engine cooling fan.

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relay 2 and 3 operates the 1 fan at a high speed Cooling Fan Relay 1, 2 and 3 operates both fans at a high speed
2. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

1. Ignition OFF, disconnect the KR20 cooling fan relays.
2. Connect a 30 A fused jumper between the KR20E cooling fan speed control relay switch circuit terminal 30 and the ground circuit terminal 87. This completes the left side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
3. Ignition ON, verify that a test lamp illuminates between ground and the relay switched ignition circuit terminal listed below: KR20C cooling fan low speed relay terminal 87 KR20D cooling fan high speed relay terminal 87 If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate KR20 relay.
4. Connect a 30 A fused jumper between the KR20 cooling fan relay circuit terminals listed below. Verify the appropriate fan is activated. KR20D cooling fan high speed relay terminals 87 and 30 KR20C cooling fan low speed relay terminals 87 and 30 If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, replace the appropriate G10 cooling fan motor. If the corresponding cooling fan activates, replace the appropriate KR20 cooling fan relay.
5. Install the KR20E cooling fan speed control relay. Verify both fans activate at low speed. If both fans do not activate, test the relay controlled output circuit terminal 87A of the KR20E cooling fan speed control relay for a short to ground or an open/high resistance.
6. If the circuits test normal, test or replace the KR20E cooling fan speed control relay.

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL. 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the KR20 cooling fan relay.
4. Test the KR20E cooling fan speed control relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the KR20E cooling fan speed control relay.
5. Install a 20 A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR20 cooling fan relay.

Thermostat Diagnosis

Special Tools

J 24731 Tempil Stick

Use one of the following procedures in testing for a malfunctioning thermostat.

Thermostat Test Procedure Using Tempil Sticks

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a pencil like device. It has a wax material containing certain chemicals which melt at a given temperature. Take a 87°C (188°F) tempil stick or a 97°C (206°F) tempil stick and rub it on the thermostat housing. Temperature sticks can be used to determine a thermostat's operating range.

1. Use a J 24731 Tempil Stick in order to find the opening and the closing temperatures of the coolant thermostat. The 188 tempil stick melts at 87°C (188°F). The thermostat should begin to open. The 206 tempil stick melts at 97°C (206°F). The thermostat should be fully open.
2. Replace the coolant thermostat if it does not operate properly between this temperature range.

Thermostat Test Procedure Using Glycol

Inspect the operation of the thermostat by hanging the thermostat on a hook in a 50/50 percent solution of DEX-COOL® and clean drinkable water.

In order to inspect if the thermostat valve is opening properly, perform the following test

1. Completely submerge the thermostat in the glycol solution. The solution should be 11°C (22°F) above the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should open.

In order to inspect if the thermostat valve is closing properly, perform the following test

1. Completely submerge the thermostat in a glycol solution. The solution should be 6°C (10°F) below the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should close completely.

1. Perform the «Diagnostic System Check - Vehicle»(ref-491140-S24065023222012073000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-491140-S09841272902012073000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-491140-S29106564382012073000000) provides an overview of each diagnostic category.

Note. The power supply cord will read open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).

1. Test the engine coolant heater for an open or short to ground. If open or shorted, replace the heater.
2. If the heater tests normal, replace the coolant heater power cord.

Pressure Cap Testing

Special Tools

1. J 24460-01 Cooling System Pressure Tester
2. J 42401-1 Radiator Cap / Surge Tank Test Adapter

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the J 24460-01 Cooling System Pressure Tester (1) with J 42401-1 Radiator Cap / 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 J 24460-01 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

1. J 24460-01 Cooling System Pressure Tester
2. J 42401 Radiator Cap/Surge Tank Test Adapter

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(ref-491221-S06896667932012073000000) .
3. Wash the pressure cap mating surface with water.
4. Use the J 24460-01 Cooling System Pressure Tester with the J 42401 Radiator Cap/Surge Tank Test Adapter in order to apply pressure to the cooling system. Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gauge for any pressure loss.
6. Repair any leaks as required.