Wiper and Washer Systems: Description and Operation

OPERATION

Multi-function Switch
The Multi-function Switch has a momentary Washer Switch, a four-position Wiper Switch and a Variable Resistor, which sets interval time.

Washer Operation
Pushing the wiper/washer control knob sends current from Circuit Breaker 2 through the Washer Switch to the Windshield Washer Pump.

LO/HI Speed Wiper
When the Wiper Switch is in the "LO" (or "HI") position, section A of the Wiper Switch powers the interval override so that the Electronic Switch and the Windshield Wiper Module Relay are pulled in continuously. Wiper Motor current then flows through Circuit Breaker 2 and the energized contacts of the Windshield Wiper Module Relay to the L terminal of the Wiper Motor. Power is applied to the H terminal of the Wiper Motor through section B of the Wiper Switch for high speed operation.

Interval Wiper
The Interval Wiper/Washer allows the driver to select "LO" speed, "HI" speed or Interval wipe. With the wipers in the interval position, wipes are spaced two to ten seconds apart.

During Interval operation, the wipers make single wipes at low speed separated by a variable length pause.

When first switched to "INT" position, section B of the Wiper Switch activates the Interval Timer. The Interval Timer momentarily closes the Electronic Switch, energizing the Windshield Wiper Module Relay. Current flows to the Wiper Motor L terminal through the energized contacts of the Windshield Wiper Module Relay. Ground is connected to terminal C of the Wiper Motor.

As the Wiper Motor turns, the Wiper Motor Switch changes from the grounded "PARK" position to the hot "RUN" position. Current now flows through the 63 (R) wire and the RUN contact of the Wiper Motor Switch, and resets the interval timer, which opens the Electronic Switch. The current path continues through the deenergized Windshield Wiper Module Relay contact to the L terminal of the Wiper Motor. Wiping continues until final wipe is completed. The Wiper Motor Switch returns to the PARK position contact, which is grounded, and the Wiper Motor stops. After a pause (controlled by the variable resistor), the Interval Timer pulls in the Windshield Wiper Module Relay to start another wiper.

When parking is complete, the wiper motor is braked to a stop by shunting the L and C terminals through the wiper motor switch. Braking takes place when the wiper motor switch moves to the "PARK" position. The wiper motor L terminal is connected to terminal C through the park contact of the wiper motor switch and the deenergized contact of the interval governor relay.