Conditions for Setting the DTCs
- An improper voltage level has been detected on the cooling fan relay control circuit.
- The condition must be present for a minimum of 5 seconds.
Reference Information
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
- «Master Electrical Component List»(ref-302330-S10597750992008102100000)
- «Component Connector End Views»(ref-302316-S39329928222008102100000)
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-302317-S14465820352008102100000)
- «Connector Repairs»(ref-302317-S07938571952008102100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-302317-S07813738172008102100000)
- «Wiring Repairs»(ref-302317-S36649915442008102100000)
- «Electrical Center Identification Views»(ref-302316-S09500421462008102100000)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, command each relay ON and OFF with a scan tool. Feel or listen to verify that each relay turns ON and OFF with each command.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Engine Coolant Fan Motor Replacement»(ref-302344-S30959482582008102100000)
- «Control Module References»(ref-302291-S24032387652008102100000)
- An improper voltage level has been detected on the cooling fan relay control circuit.
- The condition must be present for a minimum of 30 seconds.
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
- «Master Electrical Component List»(ref-302330-S10597750992008102100000)
- «Component Connector End Views»(ref-302316-S39329928222008102100000)
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-302317-S14465820352008102100000)
- «Connector Repairs»(ref-302317-S07938571952008102100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-302317-S07813738172008102100000)
- «Wiring Repairs»(ref-302317-S36649915442008102100000)
- «Electrical Center Identification Views»(ref-302316-S09500421462008102100000)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Ignition ON, command each relay ON and OFF with a scan tool. Feel or listen to verify that each relay turns ON and OFF with each command.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Engine Coolant Fan Motor Replacement»(ref-302344-S30959482582008102100000)
- «Auxiliary Engine Coolant Fan and Fan Motor Replacement»(ref-302344-S14666021202008102100000)
- «Control Module References»(ref-302291-S24032387652008102100000)
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 determine 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 is located 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 determined, refer to Testing for Intermittent Conditions and Poor Connections for specific strategies in diagnosing intermittent conditions.
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
- «Master Electrical Component List»(ref-302330-S10597750992008102100000)
- «Component Connector End Views»(ref-302316-S39329928222008102100000)
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-302317-S14465820352008102100000)
- «Connector Repairs»(ref-302317-S07938571952008102100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-302317-S07813738172008102100000)
- «Wiring Repairs»(ref-302317-S36649915442008102100000)
- «Electrical Center Identification Views»(ref-302316-S09500421462008102100000)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
- If DTCs P0691, P0692, P0693 or P0694 are set, then perform those diagnostics first.
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
- «Engine Coolant Fan Motor Replacement»(ref-302344-S30959482582008102100000)
- «Control Module References»(ref-302291-S24032387652008102100000)
Repair Verification
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
- «Master Electrical Component List»(ref-302330-S10597750992008102100000)
- «Component Connector End Views»(ref-302316-S39329928222008102100000)
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-302317-S14465820352008102100000)
- «Connector Repairs»(ref-302317-S07938571952008102100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-302317-S07813738172008102100000)
- «Wiring Repairs»(ref-302317-S36649915442008102100000)
- «Electrical Center Identification Views»(ref-302316-S09500421462008102100000)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
- If DTCs P0691, P0692, P0693 and P0694 are set, perform those diagnostics first.
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
- «Engine Coolant Fan Motor Replacement»(ref-302344-S30959482582008102100000)
- «Auxiliary Engine Coolant Fan and Fan Motor Replacement»(ref-302344-S14666021202008102100000)
- «Control Module References»(ref-302291-S24032387652008102100000)
- Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
- Ignition ON, observe that the fan is not activated.
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
- «Master Electrical Component List»(ref-302330-S10597750992008102100000)
- «Component Connector End Views»(ref-302316-S39329928222008102100000)
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-302317-S14465820352008102100000)
- «Connector Repairs»(ref-302317-S07938571952008102100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-302317-S07813738172008102100000)
- «Wiring Repairs»(ref-302317-S36649915442008102100000)
- «Electrical Center Identification Views»(ref-302316-S09500421462008102100000)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
- If DTCs P0691, P0692, P0693 or P0694 are set, then perform those diagnostics first.
- Ignition ON, command each relay ON and OFF with a scan tool. Observe to verify that the fans turn ON and OFF with each command.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Engine Coolant Fan Motor Replacement»(ref-302344-S30959482582008102100000)
- «Control Module References»(ref-302291-S24032387652008102100000)
Ignition ON, command each relay ON and OFF with a scan tool. Observe to verify that each fan turns ON and OFF with each command.
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
- «Master Electrical Component List»(ref-302330-S10597750992008102100000)
- «Component Connector End Views»(ref-302316-S39329928222008102100000)
Description and Operation
Cooling Fan Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-302317-S14465820352008102100000)
- «Connector Repairs»(ref-302317-S07938571952008102100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-302317-S07813738172008102100000)
- «Wiring Repairs»(ref-302317-S36649915442008102100000)
- «Electrical Center Identification Views»(ref-302316-S09500421462008102100000)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
- If DTCs P0691, P0692, P0693 and P0694 are set, perform those diagnostics first.
- Ignition ON, command each relay ON and OFF with a scan tool. Observe to verify that the fan turns ON and OFF with each command.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Engine Coolant Fan Motor Replacement»(ref-302344-S30959482582008102100000)
- «Auxiliary Engine Coolant Fan and Fan Motor Replacement»(ref-302344-S14666021202008102100000)
- «Control Module References»(ref-302291-S24032387652008102100000)
Ignition ON, command each relay ON and OFF with a scan tool. Observe to verify that each fan turns ON and OFF with each command.
Engine Overheating
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| DEFINITION: The engine temperature lamp comes ON and stays ON, or the temperature gage shows hot, or coolant overflows from the surge tank onto the ground while the engine is running. | ||||
| 1 | Check for a loss of coolant. Refer to Loss of Coolant . Is there a loss of coolant? | Go to Step 2 | Go to Step 3 | |
| 2 | Fill the system to the specified level. Refer to Cooling System Draining and Filling . Does the engine still overheat? | Go to Step 3 | System OK | |
| 3 | Check for kinked or pinched surge tank hoses, especially at the radiator. Are any surge tank hoses kinked or pinched? | Go to Step 4 | Go to Step 5 | |
| 4 | Relieve any kinks by rerouting the hoses. Replace the hoses if necessary. Does the engine still overheat? | Go to Step 5 | System OK | |
| 5 | Check for loose, missing, or damaged radiator air seals or deflectors. Are there any loose, missing, or damaged radiator air seals or deflectors? | Go to Step 6 | Go to Step 7 | |
| 6 | Repair or replace any loose, missing, or damaged radiator air seals or deflectors. Does the engine still overheat? | Go to Step 7 | System OK | |
| 7 | Check the coolant concentration. Does the coolant concentration test correctly? | Go to Step 9 | Go to Step 8 | |
| 8 | Replace the coolant if necessary. Refer to Cooling System Draining and Filling . Does the engine still overheat? | Go to Step 9 | System OK | |
| 9 | IMPORTANT: Use the correct pressure cap. Check the system for loss of pressure.Is there a loss of pressure? | Go to Step 10 | Go to Step 11 | |
| 10 | Repair any leaks as necessary. Does the engine still overheat? | Go to Step 11 | System OK | |
| 11 | Check for a faulty engine coolant temperature (ECT) sensor. Is the engine coolant temperature sensor faulty? | Go to Step 12 | Go to Step 13 | |
| 12 | Replace the ECT. Refer to Engine Coolant Temperature Sensor Replacement . Does the engine still overheat? | Go to Step 13 | System OK | |
| 13 | Check the radiator for any airflow obstructions or bent fins. Is there any airflow obstruction or bent fins? | Go to Step 14 | Go to Step 15 | |
| 14 | Remove or relocate add-on parts that block airflow to the radiator. Clean any debris from the radiator core. Does the engine still overheat? | Go to Step 15 | System OK | |
| 15 | Check for any blocked cooling system passages. Are there any blocked cooling system passages? | Go to Step 16 | Go to Step 17 | |
| 16 | Remove any obstruction. Flush the cooling system as required. Refill the coolant. Refer to Cooling System Draining and Filling . Does the engine still overheat? | Go to Step 17 | System OK | |
| 17 | Check for an inoperative cooling fan. Is the cooling fan inoperative? | Go to Step 18 | Go to Step 19 | |
| 18 | Replace the cooling fan motor. Refer to Engine Coolant Fan Motor Replacement . Does the engine still overheat? | Go to Step 19 | System OK | |
| 19 | Check for a thermostat that is stuck closed. Is the thermostat stuck closed? | Go to Step 20 | Go to Step 21 | |
| 20 | Replace the thermostat. Refer to Engine Coolant Thermostat Replacement . Does the engine still overheat? | Go to Step 21 | System OK | |
| 21 | Check for a faulty water pump. The impeller blades may be eroded or broken. Is the water pump faulty? | Go to Step 22 | ||
| 22 | Replace the water pump. Refer to Water Pump Replacement . Does the engine still overheat? | System OK | ||
| IMPORTANT |
|---|
| Use the correct pressure cap. |
Loss of Coolant
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: The cooling system is losing coolant either internally or externally. | |||
| 1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - Engine Cooling |
| 2 | Repair any present DTCs. Refer to Diagnostic System Check - Vehicle . Is the action complete? | Go to Step 3 | |
| 3 | Inspect the coolant level. Is the coolant at the proper level? | Go to Step 5 | Go to Step 4 |
| 4 | Fill the cooling system to the proper level. Refer to Cooling System Draining and Filling . Is the action complete? | Go to Step 5 | |
| 5 | If the engine is suspected to have a coolant leak into a cylinder, the coolant can hydraulically lock the engine. Does the engine crankshaft rotate? | Go to Step 6 | Go to Step 26 |
| 6 | Engine overheating can cause a loss of coolant. Is the engine overheating? | Go to Step 29 | Go to Step 7 |
| 7 | Extended operation with a low coolant level can cause engine internal component failure. Is the engine knocking? | Go to Step 31 | Go to Step 8 |
| 8 | Idle the engine at normal operating temperature. Inspect for heavy white smoke coming out of the exhaust pipe. Is a heavy white smoke present from the exhaust pipe? | Go to Step 9 | Go to Step 10 |
| 9 | Coolant in the exhaust system creates a distinctive, burning coolant odor in the exhaust. Condensation in the exhaust system can cause an odorless white smoke during engine warm up. Does the white smoke have a burning coolant type odor? | Go to Step 30 | Go to Step 10 |
| 10 | CAUTION: Refer to Moving Parts and Hot Surfaces Caution . With the engine idling, inspect the coolant recovery system.Does the coolant recovery system discharge coolant while the engine is idling? | Go to Step 15 | Go to Step 11 |
| 11 | Visually inspect the hoses, pipes and hose clamps at the following locations: The coolant surge tank The heater core The radiator Are any of the hoses, clamps or pipes leaking? | Go to Step 22 | Go to Step 12 |
| 12 | Visually inspect the following components: The coolant pressure cap The core plugs The cylinder head gaskets The engine block The intake manifold The radiator The thermostat housing The water pump Are any of the listed components leaking? | Go to Step 22 | Go to Step 13 |
| 13 | Pressure test the cooling system. Refer to Cooling System Leak Testing . With the cooling system pressurized, visually inspect the components listed in steps 11 and 12. Are any leaks present? | Go to Step 22 | Go to Step 14 |
| 14 | Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure? | Go to Step 16 | Go to Step 23 |
| 15 | Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure? | Go to Step 32 | Go to Step 23 |
| 16 | Inspect for the following conditions: A coolant smell inside of the vehicle Coolant in the HVAC module drain tube Coolant on the vehicle floor covering near the HVAC module Is coolant present? | Go to Step 24 | Go to Step 17 |
| 17 | Add 30 ml (1 oz) of GM P/N 89022219 (Canadian P/N 89022220) Canada Extended Life Coolant Leak Detection Dye to the cooling system for each 15 L (4 gal) of coolant. Refer to Approximate Fluid Capacities . Start the vehicle and allow the engine to reach normal operating temperature. Shut the engine off. Use J 42220 Universal 12V Leak Detection Lamp to visually inspect the components listed in steps 11 and 12. Are any leaks present? | Go to Step 22 | Go to Step 18 |
| 18 | Use J 42220 to inspect for the following conditions: Coolant dye in the HVAC module drain tube Coolant dye on the vehicle floor covering near the HVAC module Is coolant dye present? | Go to Step 24 | Go to Step 19 |
| 19 | Inspect the underside of the engine oil fill cap for a gray/white milky substance. Is a milky substance under the oil fill cap? | Go to Step 20 | Go to Step 21 |
| 20 | Inspect the engine oil fluid level indicator for a gray/white milky substance. Is a milky substance on the engine oil fluid level indicator? | Go to Step 30 | Go to Step 21 |
| 21 | Inspect the automatic transmission oil fluid level indicator, if equipped, for a gray/white milky substance. Is there a milky substance on the automatic transmission fluid level indicator? | Go to Step 25 | Go to Step 33 |
| 22 | Repair or replace the leaking component. Refer to the appropriate repair. Is the repair complete? | Go to Step 33 | |
| 23 | Replace the coolant pressure cap. Is the repair complete? | Go to Step 33 | |
| 24 | Replace the heater core. Refer to Heater Core Replacement . Is the repair complete? | Go to Step 33 | |
| 25 | Remove the transmission oil cooler lines from the radiator. Pressure test the cooling system. Refer to Cooling System Leak Testing . Inspect the transmission oil cooler for coolant. Is coolant present? | Go to Step 26 | Go to Step 27 |
| 26 | Replace the radiator. Refer to Radiator Replacement . Service the automatic transmission. Refer to Engine Coolant/Water in Transmission . Is the repair complete? | Go to Step 33 | |
| 27 | Install the cooler lines to the radiator. Is the action complete? | Go to Step 33 | |
| 28 | Repair the engine no crank condition. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate . Is the repair complete? | Go to Step 33 | |
| 29 | Repair the engine overheating condition. Refer to Engine Overheating . Is the repair complete? | Go to Step 33 | |
| 30 | Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or Coolant in Engine Oil . Is the repair complete? | Go to Step 33 | |
| 31 | Repair the engine knock. Refer to Lower Engine Noise, Regardless of Engine Speed . Is the repair complete? | Go to Step 33 | |
| 32 | Repair the combustion pressure in the cooling system problem. Refer to Coolant in Combustion Chamber . Is the repair complete? | Go to Step 33 | |
| 33 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
| CAUTION |
|---|
| Refer to Moving Parts and Hot Surfaces Caution . |
Engine Fails To Reach Normal Operating Temperature
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Check the coolant level in the radiator surge tank. Refer to Cooling System Draining and Filling . Is the coolant at the proper level? | Go to Step 3 | Go to Step 2 | |
| 2 | Add coolant to the radiator surge tank as necessary. Does the engine still fail to reach normal operating temperatures? | Go to Step 3 | System OK | |
| 3 | Check for a blockage in the coolant passages. Are there any blockages in the coolant passages? | Go to Step 4 | Go to Step 5 | |
| 4 | Flush the cooling system or flow check the radiator. Does the engine still fail to reach normal operating temperatures? | Go to Step 5 | System OK | |
| 5 | Check to see if the incorrect thermostat was installed or if it is stuck or sticks in the open position. Was the incorrect thermostat installed, or is it stuck or does it stick in the open position? | Go to Step 6 | ||
| 6 | Replace the thermostat. Refer to Engine Coolant Thermostat Replacement . Does the engine still fail to reach normal operating temperature? | System OK |
Filling Procedure
- Close the radiator drain cock by hand.
- Lower the vehicle
- Slowly add a mixture of 50/50 DEX-COOL antifreeze and deionized water to the cooling system until the coolant level reaches the lower vent hose (1) on the surge tank.
- Install the surge tank cap.
- Start the engine and allow to warm up. Allow the engine to warm up at idling speed of up to 2,500 RPM until the first radiator fan setting switches on.
- Vent the cooling system. To vent the cooling system completely, allow the engine to run for 1 minute at 2,000 RPM to 2,500 RPM. Engine speed greater than 1,500 RPM. Engine at operating temperature. Gearbox in Neutral.
- Turn the engine off and allow to cool.
- Inspect the coolant level and also fill the coolant to the "COLD" mark.
Cooling Fan Control (Single Fan)
The engine cooling fan system consists of one cooling fan and two relays. The cooling fan has 2 windings in the motor, one winding is for low speed and the other winding is for high speed. Voltage is supplied to the relays fuses. The engine control module (ECM) controls the low speed fan operation by grounding the relay control circuit. When the relay is energized, voltage is delivered to the cooling fan low speed winding. The ECM controls the high speed fan operation by grounding the relay control circuit. When the relay is energized, voltage is delivered to the cooling fan high speed winding. The cooling fan motor is grounded through its own ground circuit.
Cooling Fan Control (Dual Fan)
The engine cooling fan system consists of two cooling fans and two relays. Voltage is supplied to the relays through the 20A Fan Hi and 20A Fan Low fuses. The engine control module (ECM) controls the low speed fan operation by grounding the Fan Low relay control circuit. When the Fan Low relay is energized, voltage is delivered to both fans through resistors. The ECM controls the high speed fan operation by grounding the Fan Hi relay control circuit. When the Fan Hi relay is energized, voltage is delivered directly to both fans. The cooling fan motors are grounded through their own ground circuits.