Electric Cooling Fan

Circuit Description:

Power for the fan motors is supplied through MaxiFuse 1 in the Engine wiring Harness Junction Block 1. The cooling fan relays are energized when current flows from the PCM Bat Fuse in the Engine Wiring Harness Junction Block 1 and Fan # 3 fuse in the Engine Wiring Harness Junction Block 2 through the relay coils to ground through the PCM. The Low Speed Fans control circuit is grounded for low speed fans operation. The Low Speed Fans control circuit and the High Speed Fans control circuit are both grounded for high speed fans operation.

During low speed fans operation the PCM supplies a ground path for the Fan Cont # 1 Relay. This closes the Fan Cont # 1 Relay contacts, allowing current to flow from the battery junction block through the relay contacts to the left engine cooling fan. During low speed operation, the ground path for the Engine Coolant Fan Motor 1 is through the Fan Cont # 2 Relay and the Engine Coolant Fan Motor 2. The result is a series circuit with both cooling fans running at low speed.

During high speed cooling fan operation the PCM supplies a ground path for the Fan Cont # 1 Relay. The PCM also supplies a ground path for Fan Cont # 2 Relay and Fan Cont # 3 Relay. This closes all three cooling fan relays. During high speed fans operation, both the Engine Coolant Fan Motor 1 and 2 are supplied current from the battery junction blocks and each cooling fan has its own ground path.

For diagnostic information see Electric Cooling Fan Diagnosis under Computers and Control Systems. Component Tests and General Diagnostics