DTC P0480 or P0481 2.4

The engine control module (ECM) grounds the low speed relay, which is relay 1, and the high speed relay, which is relay 2, control circuits through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line that is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the ECM detects that the actual state of the control circuit does not match the expected state, a DTC will set.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

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

1. Ignition OFF, disconnect the affected relay.
2. Ignition ON, connect a test lamp between the positive terminal at the battery and the relay control circuit terminal.

•	Cooling Fan Relay 1 = Terminal 86

•	Cooling Fan Relay 2 = Terminal 85

3. Command the relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the 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 lamp is 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 between the positive voltage terminal at the battery and the fan voltage supply circuit terminal and verify fan activation.

•	Cooling Fan Relay 1 = Terminal 87

•	Cooling Fan Relay 2 = Terminal 30

⇒	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 between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal and verify fan activation.

For the Relay Switch Voltage Supply Circuit

•	Cooling Fan Relay 1 = Terminal 30

•	Cooling Fan Relay 2 = Terminal 87

For the Fan Voltage Supply Circuit

•	Cooling Fan Relay 1 = Terminal 87

•	Cooling Fan Relay 2 = Terminal 30

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

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

•	Cooling Fan Relay 1 = Terminal 85

•	Cooling Fan Relay 2 = Terminal 86

⇒	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, replace the relay.

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

Cooling Fan and Shroud Replacement

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.