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Home >> Chevy Truck >> 2010 >> Express 3500 V8-6.6L DSL Turbo >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0480 >> VIN 6

VIN 6




DTC P0480 (LMM)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 modulated (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 clutch is commanded ON, the control circuit is at a low voltage. When the fan clutch is commanded OFF, the control circuit is near battery voltage. The ECM uses this PWM signal to control the position of the oil control solenoid 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 of the driver, 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 (Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Cooling Fan Description and Operation (with RPO LMM) (Cooling Fan (with VIN 6)) Cooling Fan Description and Operation (W/LGH) (Cooling Fan Description and Operation (with VIN L))
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Idle the engine.
2. Command the cooling fan clutch to 10 percent with a scan tool.
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, with a scan tool.
5. Operate the engine at 1,500 RPM for 2 minutes. Observe the difference between the scan tool Fan Speed and Desired Fan Speed parameters. The difference should remain less than 1,000 RPM throughout the speed transition.
6. Observe the DTC information with a scan tool. Verify DTC P0480 is not set.
7. 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 cooling fan or fan clutch relay.
2. Test for less than 3 ohm between the fan relay ground circuit terminal K9, or relay terminal 6 and ground.

• If greater 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, connect a 10 A fused jumper wire between the cooling fan clutch supply voltage circuit terminal K11, or relay terminal 4 and 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 fan clutch.

6. Ignition OFF, connect a 10 A fused jumper wire between the relay voltage supply circuit terminal J12, relay terminal 2, and the cooling fan clutch supply voltage circuit terminal K11, relay terminal 4.
7. 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 the fuse is open, test all the components connected to the fuse and replace as necessary.

8. Ignition OFF, connect a test lamp between the cooling fan clutch relay control circuit terminal L12, relay terminal 5 and B+. The test lamp should not illuminate.

• If the test lamp illuminates, test the control circuit for a short to ground.

9. Engine operating at 1,500 RPM, command the cooling fan clutch to 80 percent for 2 minutes, with a scan tool. The test lamp should illuminate or flash, indicating that the ECM can control the relay.

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

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

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

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

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