Wiper/Washer System Operation

The windshield wiper/washer module is part of the windshield wiper motor cover and controls wiper motor operation. The accessory voltage supplied to the windshield wiper motor assembly is used to operate the wiper motor in all modes. The windshield wiper motor is a 2 speed motor and is operated at low speed in all modes except HIGH. When the wiper/washer switch is activated, battery voltage is applied through the switch contacts, a series of resistors, and through the wiper switch signal circuits to the wiper/washer module. The voltage level of these signal circuits determine the windshield wiper/washer modes of operation. The following is a list of wiper/washer modes of operation:

• Manual Low Speed:  When the wiper/washer switch is in the LOW position, battery voltage is applied through a 24K ohm resistor and the windshield wiper switch signal 2 circuit to the module. Battery voltage is also applied through the windshield wiper switch signal 1 circuit to the module. The reduced voltage from the wiper switch signal 2 circuit and voltage from the wiper switch signal 1 circuit indicates the manual low request. In response to these signals, the wiper/washer module applies voltage to its internal wiper motor LOW speed terminal and the wiper motor runs in the manual LOW speed mode.
• MIST:  Windshield wiper/washer system MIST operation is identical to LOW operation, as described above, except that the MIST switch is a press and release type. When the wiper switch is moved to the MIST position and released, low speed wiper motor operation is started and will continue until 1 cycle is complete. If the wiper switch is moved to the MIST position and held, the windshield wiper motor will operate in the LOW mode until the switch is released.
• DELAY:  Windshield wiper DELAY operation is also a low speed wiper motor function, but with a variable delay interval between the wiper motor cycles. The DELAY interval is controlled through a series of resistors within the wiper/washer switch. During DELAY wiper operation the wiper switch signal 2 circuit is at the same voltage level used for LOW speed operation, but the wiper switch signal 1 circuit voltage is reduced through the DELAY resistors. The windshield wiper/washer module uses a capacitor that is fed by the wiper switch signal 1 circuit to determine the frequency of the low speed wiper motor cycles. When the wiper switch signal 1 circuit is at a high voltage level as in the LOW switch position, the higher voltage charges the capacitor fast, causing a delayed, but continuous LOW speed wiper motor operation. The DELAY switch position indicating the longest interval between wiper motor cycles, is the switch position with the highest resistance, resulting in low voltage on the wiper switch signal 1 circuit. This low voltage charges the capacitor slowly, causing a long delay interval between wiper motor cycles. As the DELAY switch is turned to positions indicating more frequent wiper cycles, the resistance through the wiper/washer switch is reduced and the wiper switch signal 1 circuit voltage increases. When the wiper switch signal 1 circuit voltage increases the capacitor charges faster and the delay interval between wiper motor cycles decreases.
• Manual HIGH Speed:  When the wiper switch is placed in the HIGH position, battery voltage is applied through the switch contacts and the wiper switch signal 1 circuit, wiper switch signal 2 circuit, and the high speed signal circuit to the wiper/washer module. During HIGH speed wiper operation, the wiper switch signal 1 and signal 2 circuits are at the LOW speed signal voltages, but, the LOW speed signal circuit inputs to the wiper/washer module are overridden by the active HIGH speed signal circuit. In response to this signal, the wiper/washer module applies voltage to its internal wiper motor high speed terminal and the wiper motor runs in the manual high speed mode.
• WASH:  The outside moisture sensor monitors the WASH switch to determine if the wash function is selected. When active, the moisture sensor uses this information to ignore the wash water input to the algorithm. During windshield wiper/washer system WASH operation, the wiper/washer module controls the operation of both, the wiper motor and the windshield washer pump.

  When the WASH switch is pressed, battery voltage is applied through the switch contacts and the windshield wiper/washer switch signal 2 circuit to the wiper/washer module indicating the wash command. The wiper/washer module then applies battery voltage to its internal wiper motor low speed terminal and the windshield washer pump control circuit for a minimum of 3.5 seconds or as long as the WASH command is active, followed by approximately 6 seconds of wiper motor operation.

• PARK or OFF:  Windshield wiper motor park operation is controlled by the wiper/washer module using an input from the PARK switch within the wiper motor assembly. When the windshield wiper/washer switch is turned to the OFF position while the wiper motor is somewhere in mid-cycle, the wiper/washer module will continue to operate the wiper motor until the wipers reach the PARK position.
• Automatic Delay:  The wipers are normally in the PARK position. The moisture sensor determines the dewell time appropriate for the amount of precipitation on the windshield after considering the wiper switch SENSITIVITY setting. When moisture accumulation indicates a wipe is needed, the moisture sensor signals the wiper/washer module to clear the precipitation from the windshield. For all automatic delay operations the outside moisture sensor commands the wipers to operate in LOW speed for one wipe.
• Automatic Low:  Automatic LOW speed operation is utilized when the amount of precipitation on the windshield exceeds the automatic delay threshold. With a steady amount of precipitation on the windshield, the algorithm written for this threshold will prevent cycling between automatic delay and automatic LOW speed operation.
• Automatic High:  Automatic HIGH speed operation is utilized when the amount of precipitation on the windshield exceeds the automatic low threshold. With a steady amount of precipitation on the windshield, the algorithm written for this threshold will prevent cycling between automatic LOW and automatic HIGH speed operation.