For 1990-2009 cars

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, depending on cooling requirements. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G104.

During low speed operation, the ECM supplies the ground path for the low speed fan 1 relay through the fan 1 relay or low speed 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 right cooling fan. The ground path for the right cooling fan is through the cooling fan 2 relay and the left cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the ECM supplies the ground path for the fan 1 relay through the fan 1 relay low speed control circuit. The ECM supplies a ground path for the high speed fan 3 relay and the fan 2 relay through the fan 2 relay or high speed control circuit. This energizes the fan 2 relay coil, closes the relay contacts, and provides a ground path for the right cooling fan. At the same time, the fan 3 relay coil is energized closing the relay contacts, and provides battery positive voltage from the FAN 2 fuse on the cooling fan motor supply voltage circuit, to the left 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.