Front Wiper/Washer System: Notes

All front wiper and washer system functions are initiated with the control knob on the end of the multi-function switch control stalk that extends from the left side of the steering column, just behind the steering wheel. Rotating the control knob on the end of the control stalk, selects the Off, Intermittent, Auto (on models equipped with automatic wipers), Low, or High front wiper system operating modes. In the Intermittent mode, the control knob also allows the vehicle operator to select from one of six intermittent wipe intervals. In the Auto mode, the control knob also allows the vehicle operator to select from one of six automatic wiper sensitivity levels. Pressing in on the end of the control stalk momentarily activates the Mist Wipe. Pressing it in all the way will activate the windshield washers. In the Auto mode, as you increase the sensitivity of the wipers (less delay between wipes), the result will be a corresponding acknowledgment wipe to let you know you made an adjustment to the system. The multi-function switch provides hard wired resistor multiplexed inputs to the Steering Column Control Module (SCCM), for all of the wiper and washer system functions. The SCCM then sends electronic messages to the Front Control Module (FCM) over the Controller Area Network (CAN) data bus requesting the appropriate front wiper and washer system operating modes.

All the front wiper and washer system operation is controlled by the FCM logic circuits, and that logic will only allow these systems to operate when the ignition switch is in the Accessory or On positions. Battery current is directed from a B(+) fuse in the Integrated Power Module (IPM) to the wiper on/off relay and the wiper high/low relay in the PDC through a fused B(+) circuit. The FCM uses low side drivers to control wiper system operation by energizing or de-energizing the wiper high/low and wiper on/off relays. The FCM uses both high side and low side drivers to control the operation of the washer pump/motor unit. The multi-function switch circuitry receives a clean ground output from the SCCM on a multi-function switch return circuit, then provides resistor multiplexed inputs to the SCCM on an intermittent wipe mux circuit to indicate the selected wiper system mode and on a wash/beam select mux circuit to indicate the selected washer system mode.