LGH/LML
DTC P0480 (LGH/LML)
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 engine control module (ECM) pulse width modulates (PWM) a 12-volt signal from the cooling fan relay, to control the cooling fan relay ON time. The cooling fan relay varies the voltage drop across the cooling fan clutch solenoid in relation to the pulse width modulated signal from the ECM, which allows the cooling fan to operate at variable speeds.
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 cooling fan relay 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.
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 (Gas) (Description and Operation)Cooling Fan Description and Operation (Diesel) ()
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 (Control Module References) 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
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 cooling fan clutch relay.
2. Test for less than 5 ohm between the fan relay ground circuit terminal 6 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 2 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 relay controlled output circuit and the fan clutch solenoid for a short to ground, repair or replace as necessary.
• If the relay controlled output and clutch solenoid test normal, test or replace the fan clutch relay.
4. Test for 3-4 V between the relay control circuit terminal 5 and ground.
• If less than the specified range, test the relay control circuit for an open, 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.
5. Connect a 3 A fused jumper wire between the relay control circuit terminal 5 and ground. Observe the scan tool FC Ckt Short Gnd Test Status parameter. The parameter should transition from OK to Fault when the control circuit is connected to ground.
• If the parameter does not respond as specified, test the relay control circuit for a high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the cooling fan clutch relay.
Component Testing
Relay Test
1. Remove the cooling fan clutch relay.
2. Connect a 10 A fused jumper wire between relay terminal 2 and B+. Connect a jumper wire between relay terminal 6 and ground.
3. Test for less than 1 V between terminal 4 and ground.
• If greater than the specified value, replace the fan relay.
4. Connect a jumper wire between terminal 5 and ground.
5. Test for B+ between terminal 4 and ground.
• If less than the specified value, replace the fan relay.
EV Fan Clutch Solenoid Valve Test-Static
1. Disconnect the fan clutch jumper harness connector X142.
2. Test for 7-17 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 (Diesel) ()
* Control Module References (Control Module References) for ECM replacement, setup, and programming