Ford Mustang 1994-1998 Repair Guide

Electric Fan Switch


These vehicles do not use a separate cooling fan switch; the function of the cooling fan switch is integral with the Powertrain Control Module (PCM). The PCM receives a signal from the Engine Coolant Temperature (ECT) sensor, which it uses to decide when to turn the electric cooling fan on. To turn the cooling fan on, the PCM sends a signal to the Constant Control Relay Module (CCRM), which houses the cooling fan relay and relay control unit. The cooling fan relay and relay control unit operate the cooling fan until the PCM decides the fan should be turned off.


If the fan does not turn on at all, ensure that the fan fuse has not blown. If the fuse is blown, replace it with a new one.

Because the cooling fan is controlled by the Powertrain Control Module (PCM), it is difficult to test only the fan switch. The system should be inspected by a qualified automotive technician if the fan is malfunctioning. However, since the PCM utilizes the signal from the ECT, the ECT can be tested before the vehicle is taken to a professional. Testing for the ECT is located in Driveability & Emissions Controls of this repair guide. If the ECT is found to be functioning correctly, have the rest of the system inspected by a professional.