Multiplex Pulse Relay System

The purpose of the pulse relay is to supply 12-volt current to motor windings. This is accomplished by the pulse relay switch contacts. The coil circuit is completed to ground by either the dash switch or the timing circuit, depending upon the position of the dash switch.

The holding switch contacts are held open by a fin on the washer pump drive cam. When the wiper starts to run, the fin is moved away from the holding switch permitting contacts to close. Closing the contacts accomplishes a dual function:

• The capacitor is partially discharged in preparation for the next delay period. This also turns off transistor.
• A holding circuit to ground is provided for the pulse relay coil, until the wiping stroke is completed.