Park Position Operation
WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The BCM supplies voltage to signal circuit of the windshield wiper motor park switch. The BCM monitors this signal to determine if the windshield wiper motor is still operating or it has parked. The signal will be pulled to ground by the windshield wiper motor park switch while the windshield wiper motor is operating. When the windshield wiper motor has parked, the signal is at normal voltage because of the windshield wiper switch being open.