Wiper and Washer Systems: Description and Operation

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.

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 Fuse 2 through the Washer Switch to the Windshield Washer Pump.

LO/HI Speed Wiper Operation

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 Fuse 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 Operation

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 Governor Relay. Current flows to the Wiper Motor L terminal through the energized contacts of the Governor 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 contact, which is not powered, and the Wiper Motor stops. After a pause (controlled by the variable resistor), the Interval Timer pulls in the Governor Relay to start another wipe.

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 Governor Relay.