VIN L
DTC P0480 (LGH)
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
Typical Scan Tool Data
Circuit/System Description
The electro-viscous (EV) cooling fan clutch system enables the engine control module (ECM) to change the speed of the pulley driven cooling fan in relation to the engine speed. Ignition voltage is supplied directly to the fan clutch solenoid valve. The ECM uses two output drivers and a parallel circuit to directly control the EV fan clutch solenoid valve. The ECM controls the solenoid valve by pulse width modulating (PWM) the parallel control circuits to ground, with a solid state device called a driver. The ECM changes the cooling fan speed by increasing or decreasing the solenoid valve ON time, known as duty cycle.
Conditions for Running the DTC
* The ignition voltage is greater than 11 volts.
* The engine is operating.
* The engine speed is greater than 600 RPM.
* DTC P0480 runs continuously when the conditions above exist for greater than 3 seconds.
Conditions for Setting the DTC
The ECM detects that the commanded state of the ECM driver, and the actual state of the fan clutch solenoid control circuit do not match for greater than 1 second.
Action Taken When the DTC Sets
DTC P0480 is a Type B DTC.
Conditions for Clearing the DTC
DTC P0480 is a Type B DTC.
Diagnostic Aids
The scan tool FC Ckt 2 Test Status parameters can used in conjunction with the FC Ckt Test Status parameters to verify the integrity of the individual relay control circuits. If both the scan tool FC Ckt and FC Ckt 2 parameters indicate Fault in the respective Open Test Status then the condition is isolated to the portion of relay control circuit that is after the splice and common to both drivers. If Fault is indicated in only FC Ckt or FC Ckt 2, then the condition is isolated to the respective output driver and the portion of the circuit before the splice.
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. Engine operating, command the cooling fan clutch ON to 80 % and then OFF to 0 % with a scan tool. Observe the scan tool Test Status parameters listed below:
* FC Ckt Open Test Status
* FC Ckt Short Gnd Test Status
* FC Ckt Short Volts Test Status
* FC Ckt 2 Open Test Status
* FC Ckt 2 Short Gnd Test Status
* FC Ckt 2 Short Volts Test Status
The parameters should display OK or Not Run in each of the commanded states.
2. Observe the DTC information with a scan tool. Verify DTC P0480 is 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 fan clutch solenoid valve jumper harness connector.
2. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal B and ground.
• If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test the fan clutch solenoid and jumper harness for a short to ground.
3. Test for 3-4 V between solenoid control circuit terminal A and ground.
• If less than the specified range, test the control circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the relay control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Connect a 3 A fused jumper wire between the solenoid control circuit terminal A and ground. Observe the scan tool Test Status parameters listed below:
* FC Ckt Short Gnd Test Status
* FC Ckt 2 Short Gnd Test Status
Both parameters should transition from OK to Fault when the control circuit is connected to ground.
• If both parameters do not respond as specified, test the solenoid control circuit for a high resistance.
• If only one of the parameters responds as specified, test the appropriate solenoid control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
5. If all circuits test normal, test or replace the cooling fan clutch assembly.
Component Testing
EV Fan Clutch Solenoid Valve Test-Static
1. Disconnect the fan clutch jumper harness connector X142.
2. Test for 5-12 ohm between terminal B and terminal A of the jumper harness connector.
• If not within the specified range, replace the fan clutch assembly.
3. Measure the resistance between the terminals listed below. The DMM should display OL.
* B and C
* B and D
* B and E
* B and the fan clutch housing/ground
• If less than the specified range, test the circuits of the jumper harness for an open/shorted condition. If the jumper harness tests normal, replace the cooling fan clutch assembly.
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