Wiper and Washer Systems: Description and Operation

Principle of Operation

Windshield Wiper Operation
The SJB supplies power to the wiper/washer switch from the SJB fuse 25 (20 A) when the ignition key is in the ON or ACC position. The wiper/washer switch supplies power to the windshield wiper motor to the HIGH or LOW/INTERMITTENT input, depending on the wiper/washer switch position selected. The SJB also supplies power directly to the windshield wiper motor from fuse 25 (20 A) when the ignition key is in the ON or ACC position for RUN/PARK operation. When the wiper/washer switch is in the LOW, HIGH or INTERMITTENT position, power is supplied to the windshield wiper motor which moves the wipers off the park position. Once the wipers are off the park position, an internal switch in the windshield wiper motor switches to the run/park position which directs power to the wiper switch then back to the wiper motor. This maintains power to the windshield wiper motor to complete the wipe cycle. When the cycle is complete, the internal switch in the windshield wiper motor switches back to the rest position. If the wiper/washer switch is in the LOW or HIGH position, power supplied from the wiper/washer switch and another wipe cycle starts. If the wiper/washer switch is in the INTERMITTENT position, the windshield wipers remain parked until the internal relay in the wiper/washer switch supplies power to the windshield wiper motor. The internal relay supplies power after a time delay that is determined by the 1 of 9 intermittent switch settings.

Rear Window Wiper Operation
The rear wiper motor is controlled by the SJB. The SJB supplies power to the rear wiper motor from the integrated rear wiper relay. The SJB will active the relay when all of the following conditions are met:
- ignition key is in the ON position
- liftgate glass and liftgate are closed
- the wiper/washer switch is in the LOW or INTERMITTENT position.

The SJB also supplies voltage to the rear wiper motor from SJB fuse 21 (10 A) when the ignition key is in the ON position. This power feed is used to continue the wipe cycle when the wiper/washer switch is turned to the OFF position. The SJB receives inputs from the wiper/washer switch that applies ground to the low speed wipe input or applies ground to the intermittent wipe input. When either of these circuits are grounded, the SJB activates the integrated rear wiper relay and then power is supplied to the rear wiper motor to move the rear wiper motor off the park position. An internal switch in the rear wiper motor then moves to the run position which connects the accessory relay power to the rear wiper motor. When the rear wiper motor returns to the park position, the internal switch in the rear wiper motor moves back to the park position. If the wiper/washer switch is in the LOW position, the rear wiper relay is still activate and power is supplied to the rear wiper motor and the wipe cycle will start again. If the wiper/washer switch is in the intermittent position, the rear wiper relay is not activate until the predetermined dwell time has elapsed. At which time, the SJB activates the rear wiper relay and the wipe cycle will start again.

Windshield Washer System
The SJB supplies power to the wiper/washer switch from fuse 25 (20 A) when the ignition key is in the ON or ACC position. The windshield washer pump receives power from the wiper/washer switch when the wash function is turned ON The windshield washer pump has a direct ground to the chassis.

Rear Washer System
The SJB supplies power to the rear washer pump from fuse 21 (10 A) when the ignition key is in the ON or ACC position. The rear washer pump receives ground from the wiper/washer switch when the wash function is turned ON. The wiper/washer switch also signals the SJB when the rear wash is activated and the SJB will then activate the rear wiper.