Wiper Switch in "OFF" Position - Wash Button Depressed

Wash button temporarily completes park relay coil circuit to ground. This results in relay switch contacts closing, completing circuit to wiper motor from pulse relay. This starts wiper motor and prevents wiper blades from returning to park position when wash button is released. An auxiliary park relay ground circuit is provided through a transistor in timing circuit. See Figure.

Washer pump relay coil circuit is also completed to ground by wash button at same time. With this relay energized, pump is unlocked from its idling or lock-out position, starting a wash cycle. As soon as wash cycle starts, ratchet gear starts to rotate which permits override contacts to close.

Closed override switch provides an alternate path to ground for park relay. This occurs when auxiliary ground circuit, through timing circuit transistor, shuts off. Alternate park relay ground circuits are required to keep wiper motor running after wash button is released.