Front Wiper/Washer
Front Wiper/WasherHow the Circuit Works
The front wiper/washer system is a multiplex controlled system. The combination switch control unit, MICU, and relay control module are the main operation controls of the front wiper/washer system. The front and rear washer motor relays, intermittent wiper relay, and windshield wiper high relay are incorporated in the relay control module.
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 windshield 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 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 11 (in the driver's under-dash fuse/relay box) to the windshield wiper motor and intermittent wiper relay and through fuse 20 (in the driver's under-dash fuse/relay box) to the front and rear washer motor relays.
Mist
When the windshield wiper switch is moved to MIST, the signal for mist is input to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the relay control module. The relay control module supplies ground to the intermittent wiper relay energizing it. Battery voltage is supplied through the energized intermittent wiper relay and the static windshield wiper high relay to the high winding of the windshield wiper motor causing the motor to run in high. The relay control module only supplies ground long enough to make the motor start running. As soon as the motor starts running, the mechanical park/run switch built into the motor will move from PARK to RUN. With the motor running, the mechanical park/run switch is in RUN supplying battery voltage to the high winding of the windshield wiper motor through the park/run switch and static intermittent wiper and windshield wiper high relays. If the wiper switch is held in MIST for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN. When the wiper switch is released from MIST, the wipers will stop when they return to PARK due to a lack of battery voltage through the park/run switch or static intermittent wiper relay.
Intermittent
When the windshield wiper switch is moved to INTERMITTENT, the signal for intermittent and the signal for the intermittent dwell time controller are inputted to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the relay control module. The relay control module supplies ground to the intermittent wiper and windshield wiper high relays energizing them. Battery voltage is supplied through the energized intermittent wiper and windshield wiper high relays to the low winding of the windshield wiper motor causing the motor to run in low. The relay control module only supplies ground to the intermittent wiper relay long enough to make the motor start running, but continues to ground the windshield wiper high relay. As soon as the motor starts running, the mechanical park/run switch built into the motor will move from PARK to RUN. With the motor running, the mechanical park/run switch is in RUN supplying battery voltage to the low winding of the windshield wiper motor through the park/run switch, static intermittent wiper relay, and energized windshield wiper high relay. If the wiper switch is in INTERMITTENT for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN.
When the windshield wiper switch is moved to OFF, the signal for off is input to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the relay control module. The wipers will stop when they return to PARK due to a lack of battery voltage through the park/run switch or static intermittent wiper relay.
Low Speed
Battery voltage is supplied through the energized intermittent wiper and windshield wiper high relays to the low winding of the windshield wiper motor causing the motor to run in low. The relay control module only supplies ground to the intermittent wiper relay long enough to make the motor start running, but continues to ground the windshield wiper high relay. As soon as the motor starts running, the mechanical park/run switch built into the motor will move from PARK to RUN. With the motor running, the mechanical park/run switch is in RUN supplying battery voltage to the low winding of the windshield wiper motor through the park/run switch, static intermittent wiper relay, and energized windshield wiper high relay. If the wiper switch is in LOW for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN.
When the windshield wiper switch is moved to OFF, the signal for off is input to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the relay control module. The wipers will stop when they return to PARK because of lack of battery voltage through the park/run switch or static intermittent wiper relay.
High Speed
When the windshield wiper switch is moved to HIGH, the signal for high is input to the combination switch control unit and directly to the relay control module. The combination switch control unit communicates the high signal info via a multiplexed signal to the relay control module. The relay control module supplies ground to the intermittent wiper relay energizing it. Battery voltage is supplied through the energized intermittent wiper relay and the static windshield wiper high relay to the high winding of the windshield wiper motor causing the motor to run in high. The relay control module only supplies ground long enough to make the motor start running. As soon as the motor starts running, the mechanical park/run switch built into the motor will move from PARK to RUN. With the motor running, the mechanical park/run switch is in RUN supplying battery voltage to the high winding of the windshield wiper motor through the park/run switch and static intermittent wiper and windshield wiper high relays. If the wiper switch is in HIGH for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN.
When the windshield wiper switch is moved to OFF, the signal for off is input to the combination switch control unit. The combination switch control unit communicates that info via a multiplexed signal to the relay control module. The wipers will stop when they return to PARK due to a lack of battery voltage through the park/run switch or static intermittent wiper relay.
Washer
When the windshield wiper switch is moved to 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 relay control module. The relay control module energizes the front washer motor relay supplying battery voltage to the washer motor and the high winding of the windshield wiper motor receives battery voltage through the energized intermittent wiper relay and the static windshield wiper high relay: the washer motor pumps washer fluid onto the windshield and the windshield wiper motor runs in high. As soon as the wiper motor starts running, the mechanical park/run switch built in the motor will move from PARK to RUN.