P0481

Wiring Diagram:

Coling Fan Relay Control Circuit 2 (2002 Only):

P0481 - COOLING FAN RELAY CONTROL CIRCUIT 2 (2002 ONLY)
The ECM controls both cooling fan motors by controlling two drivers, which pull each cooling fan control circuit 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). When fan control 1 and 2 are commanded Off, neither cooling fan will run. When fan control 2 is On and fan control 1 is Off, both fans will run at low speed. When fan control 1 is On and fan control 2 is Off, both fans will run at medium speed. Finally, when fan control 1 and 2 are On, both fans will run at high speed. Both cooling fan motors will begin to run on low whenever the ECT is above 96°C (204°F). A/C is commanded On with a high side pressure above 1199 kPa (174 psi) gauge pressure or on high if a low/high fault exists iii the ECT sensor circuit. DTC P0481 will set if the ECM detects an open fan control 2 circuit or lower than normal feedback voltage when fan control 2 is commanded Off; or higher than normal feedback voltage when fan control 2 is commanded On.

DTC PARAMETERS
DTC P0481 will set if fan control 2 feedback voltage is less than 66 volts when fan control 2 is commanded Off;
OR
If tan control 2 feedback voltage is greater than 4.6 volts when fan control 2 is commanded On when:
^ Condition exists for longer than 0.5 seconds Engine speed is greater than 40 rpm
^ Battery voltage is between 7.5 and 15 volts DTC P048 1 diagnostic runs continuously once the above conditions have been met.

P0481 is a type C DTC

DIAGNOSTIC AIDS
To locate an intermittent problem, use Scan tool to monitor DTC P0481 LAST TEST with engine running. Wiggling wires while watching for a change from PASSED to FAILED may locate the area where an open or short to ground in the wiring may exist. These failures are only valid if fan control 2 is currently being commanded Off.

Use Scan tool to command FAN CONTROL 2 On and Off. Both cooling fans should run at low speed when only fan control 2 is commanded On.