Wiper and Washer Systems: Description and Operation

Circuit Description

FRONT WIPER & WASHER
All functions of the front wiper/washer circuit are controlled by the position of the front wiper and washer switches. The wiper switch has 4 positions : OFF, INT, LO and HI.

Wiper Operation

I. Low and High Position
The front wiper motor has separate brushes for low and high speed operation. When the wiper switch is in LO or HI position, one of two brushes is connected to ground through the wiper switch in the multifunction switch.

II. INT Position
When the wiper switch is turned to INT, the intermittent input of the ETACS is grounded and this will provide ground to the low speed brush of the front wiper motor long enough to move the wipers out of the park position. The remainder of the wipers sweep is controlled by the park circuit. The cycle repeats as long as the wiper switch is in INT. The pause interval between sweeps is determined by the solid-state timer in the ETACM. The timer is reset at the end of each sweep when the park switch returns to the at-rest position.

III. OFF position
When the wiper switch is turned OFF and the wipers are not at rest (out of PARK), the low speed brush of the front wiper motor is grounded through the wiper switch, and the park switch of the front wiper motor.

Washer operation
The front wiper motor operates as long as the washer switch is pressed. The WASH input to the ETACM is grounded when the washer switch is operated. And this will then provide ground to the low speed brushes of the front wiper motor.

REAR WIPER & WASHER
All functions of the rear wiper/washer circuit are controlled by the position of the rear wiper & washer switch and the rear intermittent wiper relay (has it own internal control circuit and controls the relay contracts). The rear window wiper and washer are turned on by depressing the button. Washer fluid is sprayed on the glass as long as the button is depressed.
1. When the "wiper" switch is depressed, the rear window wiper starts to operate continuously
2. When the "washer" switch is depressed, the rear window wiper wipes the window several times after the washer fluid sprays onto the rear window.