Wiper and Washer Systems: Description and Operation
Windshield WipersThe windshield wiper motor receives inputs from the following: multifunction switch, ignition switch, auxiliary junction box (AJB) and central junction box (CJB). The wiper and washer systems are controlled by the smart wiper motor. The wiper/washer portion of the multifunction switch is hardwired to the smart wiper motor. When the switch is moved to the desired position, the smart wiper motor processes this information and outputs the appropriate command(s) to one of the three internal relays. The relays control the wiper high and low motor speeds and washer pump actuation.
The following components are integrated into the windshield wiper motor: the windshield wiper motor module, high/low speed relay, run/park sensor (Hall-effect) and the washer pump relay.
High Speed Windshield Wipers
High speed operation is activated when the multifunction switch supplies a ground to the wiper motor module input. This ground is applied to the run/park and high/low relays contained in the wiper motor electronics, activating the relays and providing high speed operation. The windshield wiper motor module continues to cycle the windshield wiper in high speed operation until the inputs from the multifunction switch are changed from the high speed position.
Low Speed Windshield Wipers
Low speed operation is activated when the multifunction switch supplies a specific ground to the inputs of the windshield wiper motor module. The windshield wiper motor module then supplies a ground to the windshield wiper run/park relay coil, activating it. The run/park relay and high/low relay are contained in the wiper motor electronics. 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 windshield wiper motor module 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 five intermittent wiper dwell times are activated with grounds controlled by the multifunction switch inputs to the windshield wiper motor module. When in intermittent mode of operation, the wiper motor operates in low speed. Once the windshield wiper motor module receives the necessary inputs from the multifunction switch, it 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 module receives the grounded input, the motor continues to operate until Hall-effect sensor senses the wiper motor magnet, which turns off the run/park sensor output to the windshield wiper run/park software, deactivating the relay and disconnecting voltage to the wiper motor. The windshield wipers remain parked until the windshield wiper motor module completes a time-out and then repeats the intermittent windshield wiper cycle.
Default Mode
The windshield wiper motor defaults to this mode when the Hall sensor signal is lost. This can be caused by an obstruction of the windshield wipers, a binding linkage or an electronics concern. The motor will operate in either low or high speeds; intermittent operation is not available. The windshield wipers will not correctly park in this situation and must be manually walked down the glass by changing the multifunction switch input to the wiper motor module (OFF to Low).
Rain Sensor Wiper Function - Rain Sensor Module
The rain sensor module (if equipped), is located on the inside of the windshield to the right of the rear view mirror. When the ignition switch is turned to the ON position, the rain sensor module will start to communicate with the wiper motor electronics module. If the multifunction switch is set to one of the five AUTO positions, one calibration wipe will be performed by the wiper motor. If no moisture is present on the windshield, no additional wipes will occur and only low and high speed operation can be activated from the multifunction switch. The rain-sensitive wiper system will activate the wipers and adjust the wiper speed automatically by detecting the amount of moisture on the windshield. If moisture is present on the windshield, the rain sensor will provide wipe information to the wiper motor electronics module. The rate of wipes can be adjusted by selecting a different sensitivity setting on the multifunction switch. To activate the rain sensitive wiper system, the wipers must be set to one of the five sensitivity settings on the multifunction switch lever. These settings allow you to select the wiper sensitivity that best suits your needs. The lowest position (closest to OFF) is the least sensitive to moisture and the highest is the most sensitive to moisture.
Washer System
The windshield washer is activated by the internal wiper motor module when it receives a ground from the multifunction switch from the washer input. Dependent on the correct ground, the internal wiper motor module activates the windshield washer relay (internal) by grounding the respective relay coil. When the relay is activated, it connects voltage to the washer pump while the washer level switch provides ground to the washer pump.
Low Washer Fluid Level Lamp/Indicator
The low washer fluid lamp/indicator feature is controlled by the FEM and the instrument cluster. The low washer fluid switch is hardwired to the FEM. If the fluid level is low, the FEM sends a message through the SCP communication network to the instrument cluster. The instrument cluster then processes the message and outputs an audible and visual warning. If equipped with a message center, a warning message will be displayed.