Wiper and Washer Systems: Description and Operation
How the Circuit WorksLow Speed
With the ignition switch in ON (II) or START (III), battery voltage is applied to the windshield wiper motor through fuse 12 (in the Driver's under-dash fuse/relay box). When you move the wiper switch to LOW, the low speed winding of the motor is grounded through the low contact of the wiper washer switch, and the wipers run at low speed.
Park/Off
When you turn off the wiper switch, ground is provided for the low speed winding of the windshield wiper motor through the wiper switch, intermittent wiper relay, and the cam switch on the motor to G302. The wipers then run at low speed until the cam switch on the motor moves to PARK, removing the ground which stops the wipers in the park position.
High Speed
When you move the wiper switch to HIGH, the high speed windings of the windshield wiper motor are grounded through the HIGH contact of the wiper/ washer switch, and the wipers run at high speed.
Intermittent
When you move the wiper switch to INT battery voltage is applied through fuse 9 (in the driver's under-dash fuse/relay box) and the wiper/washer switch to the driver's multiplex control unit which energizes the intermittent wiper relay by applying ground to the relay coil.
The wiper sweep interval is controlled by vehicle speed and the resistance of the intermittent dwell time controller. The resistance of the controller varies from 0 to 30k ohms. The ECM (M/T) or PCM (A/T) sends a vehicle speed signal directly to the driver's multiplex control unit. Vehicle speed will determine the rate of the wiper cycle. If you set the intermittent time to the shortest delay. the wipers will change from intermittent to low speed when the speed of the vehicle reaches 12 mph (20 km/h). They will change back to intermittent operation when vehicle speed drops below 12 mph (20 km/h) again.
Mist
When you push the wiper/washer lever down and hold it, the high speed winding of the windshield wiper motor is grounded through the MIST contact in the wiper/washer switch. The wipers sweep at high speed until you release the lever. The PARKOFF function then takes over and the wipers stop in the PARK position.
Washer
When you pull the wiper/washer lever toward you. batter! voltage is applied to the windshield washer motor and the driver's multiplex control unit. The driver's multiplex control unit grounds the coil of the intermittent wiper relay. The relay, in turn, applies ground to the low speed windings of the wiper motor. The washer motor then pumps washer fluid onto the windshield and the wipers run at low speed. When you release the lever, the wipers make one more sweep and then stop.