Component Tests and General Diagnostics

Vehicles equipped with the 7.4L gasoline engine and air conditioning are also equipped with an auxiliary cooling fan that helps to maintain cool engine operating temperatures when the vehicle is in heavy traffic or under heavy loads.

Battery voltage is available to the auxiliary cooling fan control relay at all times from the RST (2) fusible link. Ignition voltage is available to the relay coil whenever the ignition switch is in START or RUN. The Auxiliary Cooling Fan Control Temperature Switch closes whenever coolant temperature gets too high. This completes a ground path for the relay coils and the relay switch closes providing battery voltage to the Fan Motor.