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 MIL/DTC
^ 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, refer to Testing for Intermittent and Poor Connections.
^ 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.

Steps 1-2:

Steps 3-11:

DTC P0480 or P0481