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DTC P0480, P0691 or P0692 (LAU)

DTC P0480, P0691 or P0692 (LAU)

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

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Cooling Fan Control Module B+ Supply P0480* P0480 - -
Cooling Fan Control Module Ground - - - -
Cooling Fan Control Module Control P0691 P0480 P0692 -
*Opens cooling fan fuse.


Circuit/System Description

The engine control module (ECM) commands the cooling fan depending on cooling requirements. The ECM controls the cooling fan speed by commanding the cooling fan control module. The cooling fan control module supplies the power and ground circuits for the cooling fan. 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 fan at the commanded speed.

Conditions for Running the DTC


The engine speed is greater than 0 RPM.

The ignition voltage is between 10-18 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 1 second.

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

The ECM has the capability of providing command to the fan module even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know when the fan is being commanded ON by the ECM.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (LF1) Cooling Fan Description and Operation (LAU)

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.
Note

There is a slight delay before the cooling fans activate.


Ignition ON, command the cooling fan ON and OFF with a scan tool. The cooling fan should respond to the commanded states.

2. Note the DTC information with a diagnostic tool. DTCs P0480, P0691 or P0692 should not set.

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.


Circuit/System Testing


1. Ignition OFF, disconnect the harness connector at the K22 cooling fan control module.

2. Verify that a test lamp illuminates between the ground circuit terminal 2 and B+.

3. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

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

5. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test or replace the K22 cooling fan control module.

6.
Note

The cooling fan speed control circuit is pulled-up to a voltage within the ECM, 3-4 volts on the control circuit is normal.


Test for 3-4 V between the control circuit terminal 4 and ground.

7. If less than the specified range, test the control circuit for an open or a short to ground. If the circuit tests normal, replace the K20 ECM.

8. If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

9. Command the cooling fan ON and OFF with a scan tool. The DMM should transition from 3-4 V when commanded OFF to less than 1 V when commanded ON to more than 70%.

10. If the circuit voltage does not correspond to the specified values, test the control circuit for a high resistance. If the circuit tests normal, replace the K20 ECM.

11. If all circuits test normal, replace the K22 cooling fan control module.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Engine Coolant Fan Replacement (LAU) Engine Coolant Fan Replacement (LF1)

Control Module References for ECM replacement, setup, and programming