P0480
DTC P0480 or P0481 (L61)
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure Diagnostic System Check - Vehicle.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach Strategy Based Diagnosis.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category Diagnostic Procedure Instructions.
DTC Descriptors
DTC P0480: Cooling Fan Relay 1 Control Circuit
DTC P0481: Cooling Fan Relay 2 Control Circuit
Diagnostic Fault Information
Circuit/System Description
The engine cooling fan system is composed of one cooling fan, 2 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes 1 resistor mounted in the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 2 speeds using two fan control circuits. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. The ECM will operate the cooling fan at either Low or High speed based on the cooling requirements.
Conditions for Running the DTC
- The ignition voltage is between 8-18 volts.
- The engine speed is greater than 40 RPM.
- The ECM driver transitions from ON to OFF or from OFF to ON.
- DTC P0480 and P0481 run continuously when the conditions above are met.
Conditions for Setting the DTC
P0480
The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.
P0481
The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.
Action Taken When the DTC Sets
DTCs P0480 and P0481 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0480 and P0481 are Type B DTCs.
Diagnostic Aids
- The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
- The scan tool cooling fan output control operates as follows:
- Cooling Fan Relay 1 operates the fan at high speed
- Cooling Fan Relay 2 operates the fan at a low speed
- When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
Reference Information
Schematic Reference
Engine Cooling Schematics Electrical Diagrams
Connector End View Reference
Cooling System Connector End Views Connector Views
Description and Operation
Cooling System Description and Operation Description and Operation
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 Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information Control Module References
Circuit/System Verification
1. Engine operating, command the cooling fan ON and OFF at high and low speed. Verify the fan turns on at each speed as commanded. You should hear or feel a click from the fan relay.
2. Observe the DTC information with a scan tool. DTC P0480 or P0481 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 both of the cooling fan relays.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay B+ supply circuits of each relay.
-> If the test lamp does not illuminate, test the appropriate relay B+ supply circuit for or an open/high resistance. If the circuits test normal and a B+ fuse is open, test the relay switched output circuit for a short to ground. If the output circuit tests normal, test or replace the cooling fan motor.
3. Connect a test lamp between B+ and the control circuit of appropriate relay listed below:
- Cooling fan low speed relay
- Cooling fan high speed relay
- The test lamp should Not illuminate.
-> If the test lamp illuminates, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the ECM.
4. Command the appropriate cooling fan relay ON and OFF with a scan tool. The test lamp should illuminate as commanded.
-> If the test lamp does not illuminate, test the control circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the ECM.
5. If all circuits test normal, test or replace the appropriate cooling fan relay.
Component Testing
1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86.
-> If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL:
- 30 and 86
- 30 and 87
- 30 and 85
- 85 and 87
-> If less than the specified range, replace the cooling fan relay.
4. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.
-> If greater than the specified range, replace the cooling fan relay.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Relay Replacement Service and Repair
- Cooling Fan and Shroud Replacement Service and Repair
- Control Module References for ECM replacement, setup, and programming Control Module References