Wiper Switch in Off Position, Wash Button Depressed

The wash button temporarily completes the park relay coil circuit to ground. This causes the relay switch contacts to close completing the circuit to the wiper motor via the pulse relay. This starts the wiper motor (to prevent the wiper blades from returning to the park position when the 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 the 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 when the auxiliary ground circuit through the timing circuit transistor shuts off.

The alternate park relay ground circuits are required to keep the wiper motor running after the wash button is released.