Principles of Operation (How Does It Work?)
PRINCIPLES OF OPERATIONFront Wiper Washer
The wiper system has four different operating modes: off mode, low speed mode, high speed mode, and interval mode.
In the off mode, there is no windshield wiper motor activity, and the windshield wiper motor is in the PARK position.
In the low speed mode, the windshield wiper motor is set to a low speed setting. The windshield wiper hi/lo relay is deactivated. The windshield wiper run/park relay is activated when the GEM provides a ground. To de-activate the run/park relay the GEM opens the circuit to the wiper run/park relay.
In the high speed mode, the windshield wiper motor is set to a high speed setting. The windshield wiper run/park and hi/lo relays are activated when the GEM provides a ground. To deactivate the run/park and hi/lo relays the GEM opens the circuit to both relays.
In the interval mode, the windshield wiper motor is set to a low speed setting. The hi/lo relay is deactivated when the GEM opens the circuit to the hi/lo relay. The windshield wiper run/park relay is activated at the beginning of each wipe when the GEM provides a ground and deactivates when the windshield wiper motor park switch reaches the run or off position.
When the multi-function switch is in the interval (INT) position, the windshield wipers will make a single sweep followed by a pause. The control knob on the end of the multi-function switch adjusts the pause from approximately 1-20 seconds. The GEM controls the windshield wiper run/park relay to control the delay time: (ground to activate and open circuit to deactivate)
Dwell Intervals For Each Switch State:
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.
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.
When the multi-function 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 multi-function switch is in the LOW or HIGH position, but the washer will be deactivated if the knob is held longer than 10 seconds.
Rear Wiper Washer
The generic electronic module (GEM) allows operation of the rear wiper functions when the ignition switch is in the RUN or ACC positions only. The GEM controls the cycling of the rear wiper motor through one external relay.
The GEM controls the cycling of the rear wiper motor through one external relay.
There are four modes of operation: off mode, interval mode, low mode and wash mode.
In the off mode, there is no liftgate wiper motor activity and the liftgate wiper motor will be in the PARK position.
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 GEM will provide a ground to the rear wiper relay to 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.