Principles of Operation
PRINCIPLES OF OPERATIONWipers and Washers
The wiper system has three different operating modes: low speed, high speed, and interval mode.
In LOW, the windshield wiper motor is set to a low-speed setting. The windshield wiper hi/lo relay is deactivated, while the windshield wiper run/park relay is activated.
In HIGH, the windshield wiper motor is set to a high-speed setting. The windshield wiper hi/lo relay and the windshield wiper run/park relay are both activated.
In the INTERVAL mode, the windshield wiper motor is set to a low-speed setting with the windshield wiper hi/lo relay deactivated. The windshield wiper run/park relay is activated at the beginning of each wipe and deactivated when the windshield wiper motor park switch reaches the RUN position.
The windshield wiper motor allows selection of either low or high speed, when selected on the steering column mounted multifunction switch. When the switch is in the LOW position, the common brush and low speed brush are used. When the switch is in the HIGH position, current bypasses part of the armature winding to the high-speed brush. When the switch is moved to the OFF position, the windshield wiper motor will continue to run at low speed until the windshield wipers park.
When the switch is in the INTERVAL position, the windshield wipers will make a single sweep followed by a pause. The control knob on the end of the multifunction switch adjusts the pause from approximately 1-20 seconds.
Vehicles equipped with a generic electronic module (GEM) are available with the speed-dependent interval wiper feature. During the interval mode, the delay between successive wipes will decrease with higher vehicle speed to compensate for increased water on the windshield glass. This feature will relieve the operator from constantly switching between interval settings.
Dwell Intervals For Each Switch State:
If the washer switch is pressed between 100 ms and 300 ms, with the mode switch in the OFF position, the wiper system will provide one low speed wipe with no wash.
To engage the windshield washer, push the knob of the multifunction switch toward the steering column. When the multifunction switch is in the OFF or INT position, the windshield wipers will run as long as the knob is depressed up to 10 seconds. When the knob is released, the washer will stop immediately, but the windshield wipers will continue to run for two to three sweeps, then return to their previous set operation. Washer engagement does not affect windshield wiper operation when the multifunction switch is in the LOW or HIGH position, but the washer will be deactivated if the knob is held greater than 10 seconds.
Feature inputs:
- ignition switch RUN position: (battery potential on both RUN and RUN/ACC inputs)
- ignition switch ACC position: (battery potential on RUN/ACC input only)
- wiper switch position: (different resistance for each mode; see Wiper Switch Resistance Values table).
- interval delay/wash switch position: (different resistance for each mode; See Interval Delay/Wash Switch Resistance Values table)
- windshield wiper motor park switch: (ground for PARK position and battery potential for RUN position)
Feature outputs:
- windshield wiper hi/lo relay control: (ground to activate and open circuit to deactivate)
- windshield wiper run/park relay control: (ground to activate and open circuit to deactivate)
- washer pump relay control: (ground to activate and open circuit to deactivate)
The generic electronic module (GEM) allows operation of the rear wiper functions when the ignition switch is in the RUN or ACC position only. When the liftgate or liftgate glass is ajar (ground potential is present at the liftgate and/or liftgate glass ajar switch), the rear wiper is moved to the PARK position (if not in this position) and deactivated. The GEM controls the cycling of the rear wiper motor through two external relays (rear wiper up relay and rear wiper down relay).
There are three modes of operation: INTERVAL, LOW, WASH, and MIST.
In the INTERVAL mode, there are two interval wiper settings to provide the rear wiper dwell times.
When the rear wiper mode/wash switch is placed in one of the intervals in the table, the GEM will activate one rear wipe cycle of the rear wiper motor. Once the wiper cycle has reached the LO position, after the initial wipe, the GEM will start a cyclical timing function with the dwell times specified in the table.
In the LOW mode, the liftgate wiper motor will cycle the rear motor continuously at a low speed setting.
In the WASH mode, when the rear wiper wash switch is pressed and held for a time greater than 100 ms, the GEM will cycle the rear wiper motor three times.
NOTE: The GEM does not control the rear washer, only the wiper.
In the MIST mode, the washer switch is pressed between 100 ms and 300 ms with the mode switch in the OFF position, the wiper system will provide one low speed wipe with no wash.
Fluid for the rear washer is supplied by a two-way washer pump located in the windshield washer fluid reservoir in the engine compartment.
The rear washer hose contains a check valve, which is located in the hose that passes through the liftgate in the rear of the vehicle. This check valve holds the entire line full of washer fluid between washer operation.