P0480

DTC P0480

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 Descriptor
DTC P0480
- Cooling Fan Speed Output Circuit




Diagnostic Fault Information






Circuit/System Description

The engine control module (ECM) sends a pulse width modulation (PWM) signal of 0-12 volts via the cooling fan clutch control circuit to the cooling fan relay. The ECM monitors the cooling fan clutch control circuit during vehicle operation. When the cooling fan is commanded on by the ECM, the control circuit is at a low voltage. When the cooling fan is commanded off, the control circuit is near battery voltage. The ECM uses this PWM to control the position of the oil control valve located inside the cooling fan clutch.


Conditions for Running the DTC

The ignition is ON.


Conditions for Setting the DTC

* The ECM detects that the commanded state and the actual state of the control circuit do not match.
* The above condition is present for at least 600 ms.



Action Taken When the DTC Sets

DTC P0480 is a Type C DTC.


Conditions for Clearing the DTC

DTC P0480 is a Type C DTC.


Reference Information
Schematic Reference

Engine Cooling Schematics ()
Connector End View Reference

Component Connector End Views
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. Idle the engine.
2. Command the Cooling Fan Clutch to 10 percent.
3. Operate the engine at 1,500 RPM for 2 minutes. The fan should be quiet to indicate the clutch is disengaged.
4. Command the Cooling Fan Clutch to 80 percent.
5. Operate the engine at 1,500 RPM for 2 minutes. The fan should be loud to indicate the clutch is engaged.



Circuit/System Testing

1. Ignition OFF, disconnect the fan relay.
2. Measure between the fan relay ground circuit terminal K9 and ground for less than 3 ohms.

• If more than the specified range, test the ground circuit for an open/high resistance.

3. Operate the engine at 1,500 RPM for 2 minutes. The fan should be quiet to indicate the clutch is disengaged.

• If not disengaged, test the cooling fan clutch supply voltage circuit for a short to voltage. If the circuit tests normal, replace the clutch.

4. Ignition OFF, install a 10A fused jumper wire between the positive terminal at the battery and the cooling fan clutch supply voltage circuit terminal B.
5. Operate the engine at 1,500 RPM for 2 minutes. The fan should be loud to indicate the clutch is engaged.

• If not engaged, test the cooling fan clutch supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test the fan clutch ground circuit for an open/high resistance. If the circuits test normal, replace the clutch.

6. Operate the engine at 1,500 RPM for 2 minutes. The fan should be loud to indicate the clutch is engaged.

• If not engaged, test the cooling fan clutch supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the clutch.

7. Ignition OFF, install a 10A fused jumper wire between the relay voltage supply circuit terminal J12 and the cooling fan clutch supply voltage circuit terminal.
8. Operate the engine at 1,500 RPM for 2 minutes. The fan should be loud to indicate the clutch is engaged.

• If not engaged, test the relay voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.

9. Connect a test lamp between the positive terminal at the battery and the cooling fan clutch relay control circuit terminal L12.
10. Engine RUNNING at 1,500 RPM, command the cooling fan clutch to 80 percent for 2 minutes. The test lamp should turn on steady or flash, indicating that the ECM can control the relay.

• If the lamp does not flash or vary correctly, test the cooling fan clutch control circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.

11. If all circuits and the ECM test normal, replace the relay.



Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Fan Clutch Replacement (Service and Repair)
* Control Module References for ECM replacement, setup, and programming