Cooling System: Description and Operation

Cooling Fan Description and Operation

Cooling Fan Control (Single Fan)

The engine cooling fan system consists of one cooling fan and two relays. The cooling fan has 2 windings in the motor, one winding is for low speed and the other winding is for high speed. Voltage is supplied to the relays fuses. The engine control module (ECM) controls the low speed fan operation by grounding the relay control circuit. When the relay is energized, voltage is delivered to the cooling fan low speed winding. The ECM controls the high speed fan operation by grounding the relay control circuit. When the relay is energized, voltage is delivered to the cooling fan high speed winding. The cooling fan motor is grounded through its own ground circuit.


Cooling Fan Control (Dual Fan)

The engine cooling fan system consists of two cooling fans and two relays. Voltage is supplied to the relays through the 20A Fan Hi and 20A Fan Low fuses. The engine control module (ECM) controls the low speed fan operation by grounding the Fan Low relay control circuit. When the Fan Low relay is energized, voltage is delivered to both fans through resistors. The ECM controls the high speed fan operation by grounding the Fan Hi relay control circuit. When the Fan Hi relay is energized, voltage is delivered directly to both fans. The cooling fan motors are grounded through their own ground circuits.