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

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 Output Circuit

DTC P0691

Cooling Fan Speed Output Circuit Low Voltage

DTC P0692

Cooling Fan Speed Output Circuit High Voltage

Diagnostic Fault Information

1. Opens left cooling fan fuse without a DTC.
2. Left fan inoperative without a DTC.
3. Opens right cooling fan fuse without a DTC.
4. Right cooling fan inoperative without a DTC.

Circuit/System Description

The engine control module (ECM) commands the speed of the cooling fans based on cooling requirements.

The ECM controls the cooling fan speed by commanding the cooling fan control modules. Each cooling fan control module is supplied power through its own fused power circuit. Each cooling fan control module is supplied ground though its own ground circuit. The ECM sends a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module interprets the signal and operates the cooling fans at the commanded speeds.

Conditions for Running the DTC

• The ignition voltage is 11 volts or greater.
• The engine speed is 400 RPM or greater.
• The ECM driver transitions from ON to OFF or from OFF to ON.
• DTCs P0480, P0691, and P0692 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.

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

K20 Engine Control Module: Scan Tool Information for scan tool information

Circuit/System Verification

NOTE: There is a slight delay before the cooling fans activate.

1. Engine operating, command the Cooling Fans from 0 % to 90 % with a scan tool.

2. Verify the G10 Cooling Fan Motors activates in each available speed.

• 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. 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

NOTE: Both cooling fan motors must be disconnected or incorrect diagnosis may result.

1. Ignition OFF, disconnect the following G10 Cooling Fan Motors.

• G10L Cooling Fan Motor Left.
• G10R Cooling Fan Motor Right.

2. Ignition ON, verify that a test lamp illuminates between the following terminals and ground.

• G10L Cooling Fan Motor Left - terminal 1
• G10R Cooling Fan Motor Right - terminal 1
• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF, remove the test lamp and turn 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 appropriate 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, remove the test lamp and turn 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 terminals listed below and ground.
   • G10L Cooling Fan Motor Left - terminal 1
   • G10R Cooling Fan Motor Right - terminal 1
   • If less than infinite resistance, repair the short to ground in the circuit.
   • If infinite resistance, replace the appropriate 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, 3 - 4 volts on the output circuit is normal.

3. Ignition OFF, disconnect the following G10 Cooling Fan Motors.

• G10L Cooling Fan Motor Left
• G10R Cooling Fan Motor Right

4. Connect a DMM, set on the diode setting, between the following terminals and ground.

• G10L Cooling Fan Motor Left - terminal 4
• G10R Cooling Fan Motor Right - terminal 4

5. Ignition ON, 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, all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.
2. Disconnect the K20 Engine Control Module harness connector X1.
3. Test for infinite resistance between the appropriate 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.

6. Command the Cooling Fan ON to 90 % with a scan tool.

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

• If 1 V or greater

1. Ignition OFF, disconnect harness connector X1 at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the appropriate 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.
3. Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
4. Test for less than 2 Ω in the G10 Cooling Fan Motor control circuit terminal 4, end to end.
   • If 2 Ω or greater, repair the open/high resistance in the control circuit.
   • If less than 2 Ω, replace the K20 Engine Control Module.

• Go to next step: If less than 1 V

8. Test or replace the appropriate G10 Cooling Fan Motor.

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 for ECM replacement, setup, and programming

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