Cooling Fan Always On

Cooling Fan Always On (LHU)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions 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 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

Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fan 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 in the appropriate engine controls subsection.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics [1][2]Cooling System

Connector End View Reference

Component Connector End Views Outside Rearview Mirror - Driver

Description and Operation

Cooling Fan Description and Operation (LEA) Cooling Fan Description and OperationCooling Fan Description and Operation (LHU) Cooling Fan Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify that DTC P0480, P0691, or P0692, is not set.

• If a DTC is set
Refer to DTC P0480, P0691, or P0692 (LHU) P0480.

• If no DTC is set.

3. Verify the scan tool Cooling Fan Motor Command parameter is 0 %.

• If 1 % or greater
Refer to Diagnostic Aids and Symptoms - Engine Cooling Symptoms - Engine Cooling for further diagnosis.

• If 0 %

4. Verify that the G10 Cooling Fan Motor is not operating.

• If the G10 Cooling Fan Motor is operating
Refer to Circuit/System Testing.

• If the G10 Cooling Fan Motor is not operating

5. All OK.

Circuit/System Testing

1. Ignition OFF.

2. Disconnect the harness connector at the G10 Cooling Fan Motor, ignition ON.

3. Verify that the G10 Cooling Fan Motor is not operating.

• If the G10 Cooling Fan Motor is not operating

4. Replace the G10 Cooling Fan Motor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Engine Coolant Fan Replacement (2.4L LEA) Engine Coolant Fan ReplacementEngine Coolant Fan Replacement (2.0L LHU) Engine Coolant Fan Replacement

* Control Module References Control Module References