Buick Regal: DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LTG)

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 P0480

Cooling Fan Speed Control Circuit

DTC P0691

Cooling Fan Speed Output Circuit Low Voltage

DTC P0692

Cooling Fan Speed Output Circuit High Voltage

Diagnostic Fault Information

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.

Conditions for Running the DTC

• The ignition voltage is greater than 11 volts.
• The DTCs run continuously once the above conditions are 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 5 seconds.

Action Taken When the DTC Sets

DTCs P0480, P0691, and P0692 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0691, and P0692 are Type B DTCs.

Diagnostic Aids

• 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.
• In order to set certain DTCs the PCM must command the Cooling Fan system On. Using the scan tool to operate the Cooling Fan will not set certain DTCs. In these cases run the vehicle until it reaches an appropriate condition for the PCM to command the Cooling Fans On.

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

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

2. 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.

• The cooling fan does not activate or increase in speed as commanded

Refer to Circuit/System Testing

• Go to next step: The cooling fan activates and increases in speed as commanded

3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset.

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

• Go to next step: If the DTC does not set

5. All OK.

Circuit/System Testing

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

2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.

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

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 B+ 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

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 infinite resistance between the B+ circuit and ground.
   • If less than infinite resistance, repair the short to ground in the circuit.
   • If infinite resistance, replace the G10 Cooling Fan Motor.

• Go to next step: If the test lamp illuminates

NOTE: The cooling fan speed output circuit is pulled-up to a voltage within the ECM, 2-3 volts on the output circuit is normal.

3. Connect a DMM, set on the diode setting, between the G10 Cooling Fan Motor control circuit terminal 4 and ground.

4. Verify the DMM reading is greater than 2.5 V or displays O.L. with the cooling fan commanded OFF.

• If 2.5 V or less

1. Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
2. Disconnect the harness connector X1 at the K20 Engine Control Module.
3. Test for infinite resistance between the G10 Cooling Fan Motor control circuit terminal 4 and ground.
   • If less than infinite resistance, repair the short to ground in the circuit.
   • If infinite resistance, replace the K20 Engine Control Module.

• Go to next step: If greater than 2.5 V or displays O.L.

5. Command the cooling fan ON to 90% with a scan tool.

6. Verify the DMM reading is less than 1 V.

• If 1 V or greater

1. Ignition OFF.
2. Disconnect the harness connector X1 at the K20 Engine Control Module, ignition ON.
3. Test for less than 1 V between the G10 Cooling Fan Motor control circuit terminal 4 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V.
4. Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
5. Test for less than 2 Ω in the circuit end to end.
   • If 2 Ω or greater, repair the open in the circuit.
   • If less than 2 Ω, replace the K20 Engine Control Module.

• Go to next step: If less than 1 V

7. Replace the K20 Cooling Fan Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Engine Coolant Fan Replacement (2.0L LTG) or Engine Coolant Fan Replacement (3.6L LGX) for G10 Cooling Fan Motor.
• Control Module References for ECM replacement, setup, and programming

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