FixVault

Timing Circuit

Consists of a diode, capacitor, variable resistor (in wiper switch), transistor and holding switch. Voltage applied to capacitor charges it. At a preset charge, transistor is turned on like a switch completing ground circuit for pulse relay coil. Pulse contacts close, wiper starts. Holding switch contacts are held open by a fin on washer pump drive cam, but when wiper operates, fin is moved permitting holding switch to close. Closing switch discharges capacitor in preparation for next delay period and turns off transistor. Closing contacts also provides a ground circuit for pulse coil until wiper cycle is completed. Wiper shuts off when fin opens holding switch contacts.

Fig 1: PULSE WIPER WIRING DIAGRAM (CADILLAC)
G09353810Courtesy of GENERAL MOTORS COMPANY