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 (in the driver's under-dash fuse/relay box) to the MICU and combination switch control unit. With the ignition switch in ON (II), battery voltage is supplied through fuse 21 (in the driver's under-dash fuse/relay box) to the MICU, the combination switch control unit, and the relay control module. Battery voltage is also supplied through fuse 20 (in the driver's under-dash fuse/relay box) 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.