P0481

Diagnostic Chart:

Schematic:

The ECM controls both cooling fan motors by controlling two drivers, which pull the fan control circuits to ground. The combination of high/low inputs to the cooling fan control module allow Off, low, medium and high cooling fan speeds. When the ECM fan control driver is Off, the cooling fan control module input is high (battery voltage). When the ECM fan control driver is On, the cooling fan control module input is low (0 volts). Both cooling fan motors will begin to run whenever the ECT is above 96°C (204°F), A/C is commanded On with the high side pressure above 1199 kPa (174 psi) or a low/high fault exists in the ECT sensor circuit. DTC P0481 sets when fan control 2 is being commanded Off and the feedback voltage at the ECM is low, or when fan control 2 is being commanded On and the feedback voltage at the ECM is high.

DTC PARAMETERS
DTC P0481 will set if fan control 2 voltage is less than 6.5 volts when fan control 2 is commanded Off when:
^ Condition exists for longer than 0.5 seconds
^ Battery voltage is between 7.5 and 15 volts
^ Engine is running

OR

DTC P0481 will set if fan control 2 voltage is greater than 4.5 volts when fan control 2 is commanded On when:
^ Condition exists for longer than 0.5 seconds
^ Battery voltage is between 7.5 and 15 volts
^ Engine is running

DTC P0481 diagnostic runs continuously with engine running.

P0481 is a (type C) DTC

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor FC RELAY 2 CKT OPEN SHORT TO GND while commanding FAN CONTROL 2 Off. When a fault (open or short to ground) exists, the Scan tool will display YES. Then, use Scan tool to monitor FC RELAY 2 CKT SHORT TO VOLTS while commanding FAN CONTROL 2 On. When a fault (short to voltage or open ECM driver) exists, the Scan tool will display YES.