Description And Operation: Operation
The wiper (right) multifunction switch uses resistor multiplexing to control the many functions and features it provides using a minimal number of hardwired circuits. The switch receives clean grounds from the Body Control Module (BCM), then provides resistor multiplexed return outputs to the BCM to indicate the selected switch positions. The BCM then sends hardwired control outputs as well as electronic switch status messages over the Controller Area Network (CAN) data bus to other electronic modules in the vehicle.
Some of the hardwired inputs and outputs of the BCM and the wiper (right) multifunction switch unit may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, the most reliable, efficient and accurate means to diagnose the BCM and the wiper (right) multifunction switch requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
Following are descriptions of how the wiper (right) multifunction switch is operated to control the functions and features it provides:
- Front Wiper Control - The right multifunction switch control knob (2) is rotated upward to one of the two continuous wiper detents or to one of the two speed sensitive intermittent wipe detents. It is rotated to the most downward detent position to select the front wiper OFF position. The right multifunction switch control stalk (1) is raised upward to the momentary front wiper MIST position. The front wiper motor will continue to operate, one complete cycle at a time, for as long as the control stalk is held in the MIST position. If the front wipers are active, the rear wipers are automatically activated whenever the transmission gear selector is placed in the Reverse position. The BCM reads the resistor multiplexed input from the wiper (right) multifunction switch, a hardwired input from the manual transmission backup lamp switch (if equipped), an electronic reverse gear selected message input from the automatic Transmission Control Module (TCM) (if equipped) and electronic vehicle speed message inputs from the Antilock Brake Module (ABM) and provides a hardwired output to control the relays that energize or de-energize the front and rear wiper motors as appropriate.
- Front Washer Control - The right multifunction switch control stalk is pulled rearward towards the steering wheel to a momentary Front Wash position to activate the washer pump/motor in the front washer mode. The washer pump/motor will continue to operate for as long as the control stalk is held in this position. If the control stalk is held in the Front Wash position for more than about half a second, the front wiper motor will begin to operate and will continue to operate for about three complete strokes after the control stalk is released. There will also be one additional front wiper stroke about six seconds after the control stalk is released. The BCM reads the resistor multiplexed input from the wiper (right) multifunction switch and provides hardwired outputs to control the washer pump/motor and the front wiper motor as appropriate.
- Rear Wiper Control - The rear wiper mode is selected when the right multifunction switch control sleeve (3) is rotated upward to the continuous wipe or the fixed interval intermittent rear wipe detent positions. It is rotated to the most downward detent position to select the rear wiper OFF position. If the front wipers are active, the rear wipers will operate in a synchronous mode at half the speed of the front wipers, or in a continuous mode whenever the transmission gear selector is placed in the Reverse position. The BCM reads the resistor multiplexed input from the wiper (right) multifunction switch and provides a hardwired output to control a relay that energizes or de-energizes the rear wiper motor as appropriate.
- Rear Washer Control - The right multifunction switch control stalk is pushed forward towards the instrument panel to a momentary Rear Wash position to activate the washer pump/motor in the rear washer mode. The washer pump/motor will continue to operate for as long as the control stalk is held in this position. If the control stalk is held in the Rear Wash position for more than about half a second, the rear wiper motor will begin to operate and will continue to operate for about three complete strokes after the control stalk is released. There will also be one additional rear wiper stroke about six seconds after the control stalk is released. The BCM reads the resistor multiplexed input from the wiper (right) multifunction switch and provides hardwired outputs to control the washer pump/motor and the rear wiper motor as appropriate.