Excursion, Super Duty Series F-250, F-350, F-450, F-550
Wipers and Washers - Excursion, Super Duty Series F-250, F-350, F-450, F-550The Generic Electronic Module (GEM) receives inputs from the following:
^ multifunction switch
^ anti-lock brake control module (Vehicle Speed Signal [VSS])
^ ignition switch
The GEM uses these inputs to control the outputs to the following:
^ windshield wiper high/low relay
^ windshield wiper run/park relay
^ windshield washer relay
^ rear wiper motor relay
^ rear window washer relay
High Speed Windshield Wipers
High speed is activated when the multifunction switch supplies ground resistance to the GEM windshield wiper inputs. The GEM then supplies ground to the windshield wiper run/park and high/low relay coils, activating the relays with voltage supplied from the ignition switch (RUN/ACCY) through the Central Junction Box (CJB). When activated the windshield wiper run/park relay switches supply voltage to the windshield wiper high/low relay. The activated high/low relay then supplies voltage to the windshield wiper motor high speed input activating the wiper motor. Once the windshield wiper motor is activated, the run/park switch (internal to the wiper motor) switches a GEM input from ground to voltage. When the GEM receives voltage from the run/park switch, it removes ground from the run/park relay coil deactivating it. The windshield wiper motor continues to operate from voltage connected through the run/park switch and the windshield wiper run/park relay. When the windshield wiper motor returns to the park position, the internal run/park switch grounds the GEM input and the GEM removes ground from the windshield wiper high/low relay coil deactivating the high/low relay and windshield wiper motor. The GEM continues to cycle the windshield wipers until the inputs from the multifunction switch are changed from the high speed position.
Low Speed Windshield Wipers
Low speed is activated when the multifunction switch supplies a specific resistance value to the GEM windshield wiper speed inputs of the GEM. The GEM then supplies ground to only the windshield wiper run/park relay coil, activating it. When the windshield wiper run/park relay is activated, the deactivated windshield high/low relay connects voltage to the windshield wiper motor low input activating the wiper motor. The GEM continues to operate the windshield wiper motor in the same manner as in high speed, but in low speed with the wiper motor connected to the low speed input.
Intermittent Speed Windshield Wipers
The intermittent wiper speed is activated with specific resistance values controlled by the multi function switch inputs to the GEM. The GEM then activates the windshield wiper run/park relay coil and switches voltage through the windshield wiper high/low relay. The high/low relay remains deactivated supplying the voltage to the wiper motor low speed input and activates the windshield wiper motor. When the windshield wiper motor returns to the park position, the internal run/park switch disconnects voltage to the wiper motor and connects to ground. This also grounds an input to the GEM. When the GEM receives the grounded input, it removes ground from the output to the windshield wiper run/park relay coil, deactivating it and disconnecting voltage to the wiper motor. The windshield wipers remain parked until the GEM completes a time-out and then repeats the intermittent windshield wiper cycle.
Speed-Dependent Windshield Wipers
The GEM responds to the windshield wiper control commands by interpreting inputs from the steering column multifunction switch. The speed dependent wipers will compensate for the extra moisture that accumulates on the windshield at higher speeds, except when the multifunction switch is in the INT 1 position. At higher speeds, the speed dependent feature shortens the delay between wipes when using the variable interval wipers. Delays will automatically adjust at speeds between 16 and 105 km/h (10 and 65 mph).
Rear Intermittent Wiper System
The rear window wiper intermittent speed is activated when the GEM receives specific resistance values controlled by the multifunction switch inputs to the GEM. The GEM then activates the rear wiper relay by momentarily grounding the relay coil. This activates the rear wiper motor by providing voltage from the Battery Junction Box (BJB). Once the rear wiper motor is activated, it's internal run/park switch connects voltage to the motor keeping it operating. When the windshield wiper motor returns to the park position, the run/park switch disconnects voltage internally from the wiper motor input reconnecting it to the GEM output. The rear window wiper remains parked until the GEM completes a time-out and then repeats the rear wiper cycle.
Washer System
The windshield washer or the rear window washer is activated by the GEM when it receives a specific resistance value from the multifunction switch between the washer inputs. Dependent on the correct input resistance, the GEM activates either the windshield washer or rear window washer relay by grounding the respective relay coil. When either relay is activated, it connects voltage to the washer pump while the deactivated relay provides ground to the washer pump. In this manner voltage polarity is reversible to achieve directional change of the washer pump and washer fluid.