Circuit Operation

Wiper/Washer System Electrical Schematics:

In addition to the features of a conventional (non- pulse) wiper system (low and high speeds), the pulse-type windshield wiper/washer system includes an operating mode in which the wipers make single sweeps with an adjustable time interval between sweeps. The time interval is controlled by a solid-state timer in the wiper motor assembly. The duration of the delay interval is determined by the delay rheostat in the wiper/ washer switch assembly.

The wiper motor is protected by a circuit breaker. If the wipers are blocked (by snow or ice, for example), the circuit breaker will open the circuit. The circuit breaker resets automatically when it cools.

Pulse Operation
With the wiper switch in "DELAY" (pulse), battery voltage is applied to the wiper motor at terminal "B" of connector C1 through the CRY wire. Voltage also is applied to terminal "F" through the PNK wire and the pulse delay resistor in the wiper/washer switch assembly. The battery voltage at terminal "B" energizes the park switch coil, which closes its contacts. In response to the voltage at terminal "F," the solid-state timer momentarily closes contact "A" in wiper motor cover assembly which applies battery voltage at terminal "B" to the contacts of the park switch, starting the wiper motor.

A mechanical arm (end of sweep input) operates contacts in the cover assembly, which causes contact "A" to open when the wipers have completed their sweep. Since the park switch coil remains energized, the 'vipers (10 not park. but remain lust above the park posit ion until the cover assembly closes contact "A" again to start another sweep.

The length of delay time between sweeps is controlled by the variable pulse delay resistor. The delay is adjustable from 0 to 2.5 seconds.

Low-speed Operation
With the wiper switch in "LO," battery voltage is applied at wiper motor connector C1 terminals "B" and "C" through the CRY and DK CRN wires. The park switch coil is again energized and battery voltage is applied to the park switch contacts and the wiper motor. which runs continuously.

High-speed Operation
With the wiper switch in the "Ill" position, battery voltage is applied directly to wiper motor terminal "A" of connector C2 without passing through the park switch contacts. Terminal "A" is connected to a separate wiper motor brush for high-speed operation. The park switch coil remains energized in the "HI" position because of the voltage present at the low-speed wiper motor brush when voltage is applied to the high-speed brush. 'the current path from the low-speed brush to the park switch coil is completed through the wiper/washer switch assembly. An open in this circuit will cause the wipers to cycle in and out of park position in "Ill" and possibly prevent low-speed operation.

When turned off from "HI," the wipers complete the last sweep at low speed and park. To do this, the wiper motor receives voltage in the "OFF" position of the wiper switch, which is applied through the DK GRN wire to terminal "C" of connector C1. The park switch is de-energized when the wiper switch is moved to "OFF," but the contacts remain closed until the wipers reach park position.

Washer Operation
When the washer switch is held "ON," battery voltage is applied to the wiper motor cover assembly through the PNK and CRY wires. The park switch is energized by the battery voltage at terminal "B" of connector C1. Cover assembly circuitry turns on the washer pump and wiper motor by closing contacts "A" and "B." The cover assembly circuitry turns the wiper motor off approximately six seconds after it interrupts power to the washer pump. If the wipers had been in "DELAY," "LO," or "Ill," they will return to that operation after the wash cycle.

Mist Operation
When the wiper switch is moved to "MIST" and released, the wipers make one sweep at low speed and return to park position. The circuit operation is the same as that of "LO"