Radiator Cooling Fan Control Module: Description and Operation

Operation of the radiator fan(s) is controlled by the Powertrain Control Module (PCM). The PCM determines the need for radiator fan operation based on input from the engine coolant temperature sensor, or operation of the A/C system.

When the PCM has determined a need for radiator fan operation, it provides a ground path on circuit C27 at the PCM. This causes the contacts in the radiator fan ON relay to CLOSE, connecting circuits A16 and C116.

The A16 circuit is the feed for the contact side of the relay and is protected by a fusible link, located near the auxiliary jumper post on the left toe box.

Circuit C116 connects to the contact side of the radiator fan LOW/HIGH relay. This relay has two sets of contacts, one for LOW speed operation, and one for HIGH speed operation.

In the normal state, power flows through the CLOSED contacts in the radiator fan ON relay (circuit C116), through the CLOSED contacts in the radiator fan LOW/HIGH relay to the radiator fan on circuit C23. Ground for the radiator fan is supplied on circuit Z1.

When HIGH speed fan operation is required, the PCM provides a ground path for circuit C137. This causes the radiator fan LOW/HIGH relay to switch and connect circuits C116 and C25. The C25 circuit connects to the HIGH speed portion of the radiator fan.