P0480

DTC P0480 or P0481

Circuit Description

- DTC P0480 is for the cooling fan 1 control circuit.
- DTC P0481 is for the cooling fan 2 control circuit.

Battery positive voltage is supplied to the cooling fan control module from the COOL FAN #1 and COOL FAN #2 fuses. The PCM/ECM controls the relays in the cooling fan control module by grounding the cooling fan 1 and cooling fan 2 control circuits.

When the PCM/ECM is commanding a fan control circuit on, the voltage potential of the control circuit should be low, near 0 volts. When the PCM/ECM is not commanding the control circuit on, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM/ECM will monitor the control circuit for the following:

- A short to ground.
- A short to voltage.
- An open circuit.
- An internally shorted or excessively low resistance cooling fan control module.

When the PCM/ECM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

Conditions for Running the DTC

- The ignition is ON.
- System voltage is between 9-18 volts.
- The control circuit is transitioned from OFF to ON or ON to OFF.

Conditions for Setting the DTC

- The PCM/ECM detects an open, a short to ground or a short to voltage on the cooling fan control circuit.
- The above conditions are present for at least 30 seconds.

Action Taken When the DTC Sets

- The PCM/ECM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
- The PCM/ECM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

Conditions for Clearing the DTC/MIL

- The PCM/ECM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
- The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
- The DTC can be cleared by using the scan tool.

Diagnostic Aids

- If the condition is not present, See intermittent conditions.
- Review the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.