Theory Of Operation

The Body Control Module (BCM) supplies an ignition switch output circuit to the window switches. This circuit is called the Window Switch Supply circuit. If there is a short to ground or over current on this circuit, the internal relay will open up thereby protecting the BCM from damage. Once the over current is removed the circuit will return to normal by cycling the ignition from on to off then back on. This circuit is also used for the window switch lamp illumination.