Wiper and Washer Systems: Description and Operation

PURPOSE
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.

DESCRIPTION
The Interval Wiper/Washer Switch has a momentary Washer Switch, a four-position Wiper Switch, and a Variable Resistor which sets interval time.

OPERATION
Washer Operation
Pushing the Wiper/Washer control knob sends curent from Circuit Breaker 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 input so that the Electronic Switch and the Governor Relay are pulled in continuously. Wiper Motor current then flows through Circuit Breaker 2 and the energized contacts of the Governor Relay to the L terminal of the Wiper Motor.

For high speed operation, power is applied to the H terminal of the Wiper Motor through section B of the Wiper switch.

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 to the hot "RUN" position. Current now flows through the 63 (R) wire, the "RUN" contact of the Wiper Motor Switch, and resets the Interval Timer, opening the Electronic Switch.

The current path continues through the deenergized Governor Relay contact to the L terminal of the Wiper Motor. Wiping continues until the final wipe is complete.

The Wiper Motor Switch returns to the "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" connection of the Wiper Motor Switch and the deenergized contact of the Governor Relay.