Wiper and Washer Systems: Description and Operation

How the Circuit Works

The wiper/washer system is part of the multiplex integrated control system. The Driver's MICU, Passenger's MICU, and the Wiper/Washer Switch are the main operation controls of the wiper/washer system. The Windshield Wiper Relay, Intermittent Wiper Relay, and Windshield Wiper High/Low Relay are incorporated in the Under-hood Fuse/Relay Box.

Testing of the multiplex components and reading Diagnostic Trouble Codes (DTCs) can be done by using an HDS Tester. The Windshield Wiper Motor and Windshield Washer Motor also can be tested manually without an HDS Tester.

Power Supply

Battery voltage is supplied at all times to the Windshield Wiper Relay contacts through Multi-fuse 3 (in the under-hood fuse/relay box). With the ignition switch in ON (II) or START (III), battery voltage is supplied to the Driver's MICU and the Passenger's MICU through fuse 5 (in the driver's under-dash fuse/relay box). With the ignition switch in ON (II) or START (III), battery voltage is also supplied to the Windshield Wiper Relay coil through fuse 4 (in the driver's under-dash fuse/relay box) and to the Windshield Washer Relay through fuse 3 (in the driver's under-dash fuse/relay box).

Mist

When the Windshield Wiper Switch is moved to MIST the signal for mist is input to the Driver's MICU. The Driver's MICU provides ground to the Intermittent Wiper Relay coil, energizing the relay. Battery voltage is supplied through the energized Intermittent Wiper Relay and the static Windshield Wiper High/Low Relay to the high winding of the Windshield Wiper Motor, causing the motor to run in high. 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, removing ground from the motor input to the Driver's MICU. If the switch is held in MIST for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN, indicating what position the wipers are in to the Driver's MICU.

Intermittent

When the Windshield Wiper Switch is moved to INTERMITTENT, the signal for intermittent and the signal for the intermittent dwell time controller are input to the Driver's MICU. The Driver's MICU provides ground to the Intermittent Wiper Relay coil and the Windshield Wiper High/Low Relay coil, energizing the relays. Battery voltage is supplied through the energized Intermittent Wiper Relay and the energized Windshield Wiper High/Low Relay to the low winding of the Windshield Wiper Motor, causing the motor to run in low. 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, removing ground from the motor input to the Driver's MICU. If the switch is in INTERMITTENT for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN, indicating what position the wipers are in to the Driver's MICU.

Low Speed

When the Windshield Wiper Switch is moved to LOW, the signal for low is input to the Driver's MICU. The Driver's MICU provides ground to the Intermittent Wiper Relay coil and the Windshield Wiper High/Low Relay coil, energizing the relays. Battery voltage is supplied through the energized Intermittent Wiper Relay and the energized Windshield Wiper High/Low Relay to the low winding of the Windshield Wiper Motor, causing the motor to run in low. 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, removing ground from the motor input to the Driver's MICU. If the switch is in LOW for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN, indicating what position the wipers are in to the Driver's MICU.

When the Windshield Wiper Switch is moved to OFF, the signal for off is input to the Driver's MICU. Once the wipers reach the PARK position, the Driver's MICU removes the ground from the Intermittent Wiper Relay, de-energizing the relay. De-energizing the Intermittent Wiper Relay removes battery voltage from the Windshield Wiper Motor.

High Speed

When the Windshield Wiper Switch is moved to HIGH, the signal for high is input to the Driver's MICU. The Driver's MICU provides ground to the Intermittent Wiper Relay coil, energizing the relay. Battery voltage is supplied through the energized Intermittent Wiper Relay and the static Windshield Wiper High/Low Relay to the high winding of the Windshield Wiper Motor, causing the motor to run in high. 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, removing ground from the motor input to the Driver's MICU. If the switch is in HIGH for multiple wiper cycles, the PARK/RUN switch will alternate between PARK and RUN, indicating what position the wipers are in to the Driver's MICU.

When the Windshield Wiper Switch is moved to OFF, the signal for oft is input to the Driver's MICU. Once the wipers reach the PARK position, the Driver's MICU removes the ground from the Intermittent Wiper Relay, de-energizing the relay. De-energizing the Intermittent Wiper Relay removes battery voltage from the Windshield Wiper Motor.

Washer

When the Windshield Washer Switch is moved to WASH, the signal for wash is input to the Driver's MICU. The Driver's MICU communicates the wash signal via B-CAN to the Passenger's MICU. The Passenger's MICU provides ground to the Windshield Washer Relay coil, energizing the relay. Battery voltage is supplied through the energized Windshield Washer Relay to the Windshield Washer Motor, causing the motor to pump washer fluid onto the windshield. Meanwhile, the Driver's MICU provides ground to the Intermittent Wiper Relay coil, energizing the relay. Battery voltage is supplied through the energized Intermittent Wiper Relay and the static Windshield Wiper High/Low Relay to the high winding of the Windshield Wiper Motor, causing the motor to run in high. As soon as the motor starts running, the mechanical park/run switch built into the motor will move from PARK to RUN.