Wiper Circuit Operation

CIRCUIT OPERATION
The intermittent windshield wiper system is powered by a 20 Amp fuse located in the fuse block. This fuse is HOT in the RUN and ACCESSORY position. This system has three modes of operation, INTERMITTENT, LOW and HIGH.

When the ignition switch is in the RUN or ACCESSORY position, power is supplied on the F13 circuit to the windshield wiper switch and wiper motor. The wiper motor is case grounded and the switch logic and relay control uses its own ground on the Z2 circuit to the right instrument panel center support.

When the operator moves the switch to LOW speed position, battery voltage is passed through the switch to circuit V3, which connects to the LOW speed brushes of the wiper motor. If the switch is moved to the HIGH speed mode of operation, power is switched to the V4 circuit and to the HIGH speed brushes of the motor

When the delay mode of operation is selected circuits internal to the switch power up the logic and relay control. The internal control supplies power to the LOW speed area of the switch (V3 circuit) and cycles the wipers. The amount of delay between wiper cycles is dependent on switch position. All relays and internal logic in the switch are not serviceable and should be replaced as an assembly.

As the windshield wiper motor turns, the park switch internal to the motor moves from its grounded position to the powered RUN position. When the wiper switch is turned OFF, the V5 circuit is used to prevent the wipers from stopping in any position but park.

The intermittent windshield wiper system is also equipped with a pulse wipe feature. To activate this feature the operator presses the washer switch momentarily. When the washer switch CLOSES, a voltage signal is sent to the internal logic and relay control. The control will cycle the wipers. In addition, the wipers are placed in the maximum delay position.

The windshield washer uses a pump motor inside of the windshield washer fluid reservoir. When the washer switch is pressed, power is supplied on the V10 circuit to the pump motor. Ground for the pump motor is the Z1 circuit and terminates at the left headlamp ground.