The engine cooling fan system consists of one cooling fan and one relay. The relay is powered by the battery positive voltage circuit and controlled by a switched ground from the engine control module (ECM).

During operation, the ECM supplies the ground path for the cooling fan relay, which is relay 1, through the cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and supplies battery positive voltage from the cooling fan fuse through the cooling fan motor supply voltage circuit to the cooling fan. The cooling fan motor is grounded through its own ground circuit.

DTC P0480 is a Type B DTC.

DTC P0480 is a Type B DTC.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Ignition ON, command the relay ON and OFF with a scan tool. Feel or listen to verify that the relay turns ON and OFF with each command.

1. Ignition OFF, disconnect the relay.

Important: This driver may not illuminate some test lamps due to current protection. Connect two lamps in series to reduce current.

2. Ignition ON, connect two test lamps in series between the positive terminal at the battery and the relay control circuit terminal at the relay connector.
3. Command the relay ON and OFF with a scan tool. A test lamp should turn ON and OFF when changing between the commanded states.

⇒	If a test lamp is always ON, test the relay control circuit for a short to ground. If the circuit tests normal, replace the ECM.

⇒	If the test lamps are always OFF, test the relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

4. Connect a 30A fused jumper wire between the positive voltage terminal at the battery and the fan voltage supply circuit terminal and verify fan activation.

⇒	If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fan.

5. Ignition ON, connect a 30A fused jumper wire between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal and verify fan activation.

⇒	If the fan does not activate, test the relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and it's fuse is open, test all connected components and replace as necessary.

6. Ignition ON, verify that a test lamp illuminates between the relay coil voltage supply circuit terminal and ground.

⇒	If the test lamp does not illuminate, test the relay coil 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.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.