Relay, Wiper, On And Off: Operation

The wiper On and Off relay within the front Power Distribution Center (PDC) switches the input to the wiper high and low relay from a fused B (+) circuit. The Body Control Module (BCM) controls the electromagnetic coil of the relay using a High Side Driver (HSD). When the electromagnetic relay coil is energized, it draws and holds the normally open movable contact of the relay against the fixed relay contact. When the BCM de-energizes the electromagnetic relay coil, spring pressure returns the movable contact to the normally open position.

The closed relay contacts direct fused battery current from the front PDC to the wiper high and low relay. The resistor within the relay is connected in parallel with the electromagnetic coil, and helps to dissipate voltage spikes that are produced when the coil is de-energized.

The hard wired inputs and outputs of the wiper On and Off relay within the front PDC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the BCM or the electronic controls and communication between modules and other devices that provide some features of the BCM-controlled wiper On and Off relay. The most reliable, efficient and accurate means to diagnose the BCM or the electronic controls and communication related to BCM-controlled wiper On and Off relay operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.