Buick Regal: Cooling Fan Always On (Dual Fan)

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 two electric cooling fans and a cooling fan control module.

The engine control module (ECM) controls the fan speeds 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 motors in relation to the pulse width modulated signal, which enables cooling fan operations at variable speeds. The ECM will only operate the cooling fans 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

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.

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

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

Component Connector End View 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 P0480, P0691, or P0692, is not set.

• If a DTC is set

Refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LTG) or DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LGX).

• Go to next step: If no DTC is set.

3. Verify the scan tool Cooling Fan Motor Command parameter is less than 4 %.

• If 4 % or greater

Refer to Diagnostic Aids and Symptoms - Engine Cooling for further diagnosis.

• Go to next step: If less than 4 %

4. Verify that the G10 Cooling Fan Motors are not operating.

• If the G10 Cooling Fan Motors are operating

Test or replace the appropriate G10 Cooling Fan Motor.

• Go to next step: If the G10 Cooling Fan Motors are not operating

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Engine Coolant Fan Replacement (2.0L LTG) or Engine Coolant Fan Replacement (3.6L LGX) for G10 Cooling Fan Motor Replacement.
• Control Module References.

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