Circuit/System Description

The rear wiper motor is controlled by the body control module (BCM) via a printed circuit board (PCB) relay. The BCM will respond by commanding the specific rear wiper function based on an input from the rear wiper switch, which is part of the windshield wiper/washer switch. The rear wiper switch uses a resistor ladder to determine low speed, intermittent, and rear washer operation. A constant B+ and ground are supplied to the rear wiper motor. When the rear wiper switch is placed in the low speed, intermittent, or rear washer position, the voltage is pulled down through a different resistor in the resistor ladder, reducing the voltage seen at the BCM.

The BCM monitors the liftgate ajar signal circuit, and the BCM will disable the function of the rear wiper motor if the liftgate of liftglass is ajar or open