The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel (S/P) configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block.

During low speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the FAN 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the S/P fan relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the ECM continues to supply battery positive voltage for the left cooling fan by grounding the coil of the low speed cooling fan relay. The ECM also grounds the high speed fan relay and the S/P fan relay through the high speed cooling fan relay control circuit. This energizes the S/P fan relay coil, closes the relay contacts, and provides a direct ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and providing battery positive voltage from the FAN 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.