Wiper and Washer Systems: Description and Operation

OPERATION
The interval wiper/washer system allows the driver to select LO speed, HI speed, or interval (INT) wiping action. In INT, the wipes can be spaced one to fifteen seconds apart.

During washer operation, with the wiper switch in the LO or HI position during washer operation, normal wiping action occurs. If the wiper switch is in the OFF or INT position during washer operation, the wipers operate in LO speed. The wipers will continue to operate in LO speed for a few cycles after the washer button is released to dry off the windshield. The wipers then return to OFF or INT operation.

With the wiper switch in the HI position, current flows from the ignition switch through the wiper switch and governor, to the wiper motor, to ground.

With wiper switch in LO position, current flows from the ignition switch through the wiper switch and energized relay contacts of the governor, to the wiper motor.

Park Test:

When the wiper switch is placed in the INT mode, the wiper motor park switch contacts are at ground (assuming wipers started in PARK position), and the relay is energized. Initially, current flows from the ignition switch through the circuit breaker in the wiper switch, through a diode and energized contacts in the governor, to the wiper motor low speed brush. The motor rotates 1/10 of a cycle. The wiper motor park switch contacts then change from PARK (ground) to RUN (B+).

After the contacts change position, the relay in the governor de-energizes. The motor rotates through the remaining 9/10 of one cycle. When the park switch contacts again touch ground (PARK), the motor parks. The governor electronic circuit delays energizing of the relay until the circuit times out. The relay then energizes and the low-speed interval is repeated. The discharge rate of a capacitor to ground through the wiper switch variable resistor controls the time delay of the system.

CONSTRUCTION
The interval wiper system is contains the multifunction switch, a circuit breaker, wiper motor and linkage, interval governor, and a wiring harness.

The washer system contains the multifunction switch, a circuit breaker, washer pump, fluid reservoir and hoses, fluid nozzles, and a wiring harness.