Wiper Switch in "OFF" Position Wash Button Depressed

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

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

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