When the washer button is depressed two simultaneous functions occur. The washer pump motor circuit is completed to ground, and the windshield wiper unit dash switch is mechanically operated to the "on" position starting the wiper.

When the washer pump motor starts, the pump rapidly builds up pressure which closes a ball type valve. This prevents additional water from entering the pump reservoir. Water pressure closes the pressure switch which acts as a holding switch to maintain pump motor operation until the water is exhausted from the pump reservoir.

Fig. 15 - Windshield Washer (cross-section)

When the water is exhausted from the pump reservoir the pressure drops, allowing the pressure switch to open, stopping the pump motor. At the same time, the soft rubber check ball type valve opens, allowing the pump reservoir to fill with water for the next wash cycle.

The wiper unit must be turned off manually at the dash switch at the completion of a wash cycle.

The reservoir cover, pump, motor and pressure switch are all serviced as one assembly.

Duo-Speed Electric Wipers and Washer

The optional Duo-Speed Electric WIndshield Wiper consists of a compound 12 Volt DC motor and a gear box which also houses the control relay. A windshield washer installation is furnished with Duo-Speed Wiper option.

The washer pump mounts on the gear box section of the wiper and is driven by the wiper gear assembly.

Wiper Operation

The control relay and switch assembly located in the gear box section, control the starting and stopping of the wiper through a latching mechanism

Turning the instrument panel control knob to the "Lo" speed position connects the motor shunt field circuit direct to ground.

Moving the panel control to the "Hi" speed position opens the shunt field circuit to ground at the dash control switch. The shunt field circuit is then completed to ground through a resistor on the wiper unit terminal board. Grounding the shunt winding through a resistor provides increased current flow through the armature to produce the higher speed.

Washer Pump Operation

During normal operation of the wiper the washer unit pumping mechanism is held in an idling position by a relay mechanism located in the washer assembly housing.

Pushing the washer button on the instrument panel closes the washer relay circuit and mechanically operates the wiper dash control switch to the "Lo" speed position.

If the wiper is turned on prior to pushing the washer button the wiper will operate at whatever speed the dash control was set at during the wash cycle.

When the washer relay armature pulls in, the pumping mechanism is released from its idling position and starts to pump water. The diaphragm type pump is operated by a cam and link, and produces about 12 intermittent squirts of water. As the pumping mechanism starts to pump water it also starts to rotate a 21 tooth ratchet wheel. When the ratchet wheel has been rotated through the 21 teeth it returns the pump to its idling position.

At the completion of a wash cycle the wiper must be turned off manually at the instrument panel control.

Complete wiper and washer service information, including diagnosis and overhaul, is shown in the Shop Manual Supplement.

CORVETTE FOLDING TOP

A new rubberized fabric is featured for the Corvette folding top. THe new material permits the top, when folded, to lie flat in the top well. Manual folding effort is reduced because of the material's lightness.

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