The Wiper / Washer System consists of the following components:

The body control module (BCM) is part of the windshield wiper motor system and controls the wiper motor operation. The windshield wiper motor is a 2 speed motor. Windshield wiper intermittent operation is a low speed wiper motor function with a variable delay interval between the wipe cycles. The intermittent interval is controlled through a series of resistors within the wiper / washer switch. During intermittent wiper operation the windshield wiper switch low signal circuit is at the same circuit used for LOW operation.

Battery positive voltage is applied from the WIPER/WS fuse to the switch side of the WIPER relay. Battery positive voltage is also applied from the body control module (BCM) to the WIPER and WIPER HIGH relay coil circuits when commanded by the wiper switch.

Ground is applied continuously from G200 to windshield wiper motor and to the coil sides of the WIPER and WIPER HI relays. The BCM also provides a ground to the windshield wiper/washer switch.

With the wiper switch in the low position, the body control module (BCM) detects a signal in the windshield wiper switch low signal circuit. The BCM then applies voltage to the WIPER relay control circuit. This energizes the WIPER relay and allows voltage to be applied through the switched contacts of the of the WIPER relay to the normally open switched contacts of the WIPER HI relay. Voltage is then applied from the WIPER HI relay normally open contacts to the low control circuit of the windshield wiper motor.

With the wiper switch in the high position, the body control module (BCM) receives two signals, one from the windshield wiper switch low signal circuit and one from the windshield wiper switch high signal circuit. When the BCM detects these two signals, the BCM then applies voltage to the wiper high speed relay control circuit. This energizes the WIPER relay and allows voltage to be applied from the switched contacts of the WIPER relay to the high control circuit of the wiper motor.

Windshield wiper delay operation is a low speed wiper motor function which a variable delay interval between the wiper motor cycles. The delay interval is determined by a series of resistors within the wiper/washer switch. During delay wiper operation, the windshield wiper switch low signal is reduced through the delay resistors. The body control module (BCM) monitors the signal circuit to determine the delay interval between the low speed wiper motor cycles. If the wiper switch is moved from a longer delay interval to a shorter delay interval, the BCM will command an immediate wipe cycle, and reset the delay timer to the shorter delay interval.

Windshield wiper motor park operation is controlled by the body control module (BCM) using an input from the park switch within the wiper motor assembly. The BCM monitors the windshield wiper motor park switch circuit to determine if the windshield wiper blades are at the bottom of the windshield. The circuit will be pulled to ground by the wiper motor park switch while the windshield wiper motor is in operation. When the wiper switch is turned to the OFF position while the wiper motor is somewhere in mid-cycle, the BCM will continue to operate the motor until the wipers reach the park position. If the ignition is turned off while the wipers are in mid-cycle, the wipers will stop immediately where they are. The BCM will park the wipers the next time the ignition is cycled to the ON position. The BCM provides stall protection for the wiper motor by monitoring the park switch. If the park switch does not transition for 3 seconds while the wipers are in operation, the BCM will assume the at the wiper motor is stalled, and will de-energize the WIPER relay until the wiper switch is cycled off an on again.

Windshield wiper/washer system MIST operation is identical to LOW operation, except that the MIST switch is a press and release type switch. 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 wiper motor will operate in the LOW mode until the switch is released. In the MIST position, ground is supplied through an internal resistor to the windshield wiper switch low signal circuit to the body control module (BCM). The BCM will energize the WIPER relay that operates the windshield wiper motor at low speed.

In the WASH position the windshield wiper / washer switch supplies a ground signal to the body control module (BCM) through the windshield washer switch signal circuit. The BCM will energize the WIPER relay that operates the windshield wiper motor at low speed and the BCM then applies voltage to the windshield washer fluid pump. The washer pump will function for as long as the washer switch is applied. The wiper motor will continue to operate for approximately 2 wipe cycles after the wash switch is released.

The low washer fluid indicator is located in the instrument panel cluster (IPC). Ground is applied at all times from G100 through the windshield washer fluid level switch, to the low washer fluid indicator signal circuit to the body control module (BCM). When the washer fluid is low, ground is removed from the low washer fluid indicator signal circuit to the BCM. The BCM then applies a message along the class 2 serial data circuit to the IPC. The IPC then illuminates the low washer fluid indicator.