Radiator Cooling Fan Motor: Description and Operation

CIRCUIT OPERATION

The radiator fan system uses two relays located in the Power Distribution Center (PDC). One relay is used for LOW speed fan operation and the other is for HIGH speed operation. The Powertrain Control Module (PCM) controls the operation of the relays depending on engine coolant temperature and/or A/C operation.

Power for the coil side of both relays is provided on circuit F18. This circuit is protected by a 10 amp fuse located in cavity 6 of the junction block. Power for the contact side of the relays is provided on circuit A16. This circuit is protected by a 40 amp fuse located in cavity D of the PDC.

When LOW speed fan operation is required, the PCM grounds circuit C24. This causes the contacts in the relay to CLOSE connecting circuits A16 and C23. Circuit C23 connects from the relay, and is spliced to the low speed fan motor and the Radio Frequency Interference (RFI) suppression module. Ground for the motor is provided on circuit Z1, which terminates at the left front frame rail.

When HIGH speed fan operation is required the PCM grounds circuit C27. This causes the contacts in the relay to CLOSE connecting circuits A16 and C25. Circuit C25 connects from the relay, and is spliced to the high speed fan motor and the RFI suppression module. Ground for the motor is provided on circuit Z1, which terminates at the left front frame rail.