Rear Wiper/Washer

Rear Wiper/Washer

How the Circuit Works
The rear wiper/washer system is a multiplex controlled system. The combination switch control unit, MICU, MICU-rear junction box control unit and relay control module are the main operation controls of the rear wiper/washer system. The front and rear washer motor relays are incorporated in the relay control module. The rear window wiper relay is located in the MICU-rear junction box.

Testing of the control unit components and the reading of Diagnostic Trouble Codes (DTC's) within the multiplex integrated control system can be done by using a HDS Tester. There are more than 80 multiplex system DTC's. The rear window wiper motor and washer motor can still be tested manually without a HDS Tester.

Power Supply
Battery voltage is supplied at all times through fuse 7 to the MICU and combination switch control unit. With the ignition switch in ON (II), battery voltage is supplied through fuse 21 to the MICU, the combination switch control unit, and the relay control module. Battery voltage is also supplied through fuse 20 to the rear window wiper motor, rear window wiper relay and front and rear washer motor relays.

Rear Window Wiper
When the rear window wiper/washer switch is moved to RR WIP, the signal for wipers on is input to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the MICU-rear junction box control unit and relay control module. The MICU-rear junction box control unit energizes the rear window wiper relay supplying battery voltage to the winding of the rear window wiper motor causing the motor to run. The MICU-rear junction box control unit only energizes the rear window wiper relay long enough to make the motor start running. As soon as the motor starts running, the mechanical park/run switch built in the motor will move from PARK to RUN. With the motor running, the mechanical park/run switch is in RUN. If the switch is in RR WIP for multiple wiper cycles, the PARK/RUN signal will alternate between PARK and RUN indicating what position the wipers are in to the MICU-rear junction box control unit.

Rear Window Washer
When the rear window wiper/washer switch is moved to RR WASH, the signal for wash is input to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the MICU-rear junction box control unit and relay control module. The relay control module energizes the rear washer motor relay supplying battery voltage to the washer motor and the MICU-rear junction box control unit energizes the rear window wiper relay supplying battery voltage to the winding of the rear window wiper motor: the washer motor pumps washer fluid onto the rear window and the rear window wiper motor runs. As soon as the wiper motor starts running, the mechanical park/run switch built in the motor will move from PARK to RUN.