Wiper/Washer System

WIPER/WASHER SYSTEM DESCRIPTION AND OPERATION

WIPER/WASHER SYSTEM COMPONENTS
The Wiper/Washer System consists of the following components:
- Windshield wiper/washer switch
- Body control module (BCM)
- Wiper HI/LO relay
- Wiper ON/OFF relay
- Wiper diode
- Windshield wiper motor
- Windshield washer pump
- Windshield washer nozzles
- Windshield washer solvent container
- Windshield wiper arm and blade assemblies
- Windshield wiper transmission
- WIPER/SW 10A fuse
- WIPER 30A fuse
- W/S 15A fuse

Refer to Wiper/Washer System Component Views.

WIPER/WASHER SYSTEM DESCRIPTION
From switch inputs, the body control module (BCM) controls wiper motor low speed and delay operations. The washer pump and high speed operation are controlled directly by the wiper/washer switch. When the windshield wiper/washer switch is activated, battery voltage is applied from the 10A WPR/WASHER fuse, through the switch contacts, a series of resistors and through the wiper switch low signal circuit to the BCM for windshield wiper operation. When WASH, MIST, DELAY, or LOW signal is detected, the BCM energizes the wiper ON/OFF relay by applying voltage through the windshield wiper switch signal 2 circuit to the relay coil. This allows battery positive voltage from the WIPER fuse to flow through the relay input, the switch contacts, and out to the input of the wiper HI/LO relay. Since the wiper HI/LO relay is de-energized and it's switch contacts are closed to the low speed circuit of the windshield wiper motor, the motor will operate at low speed.

WASH OPERATION
When the windshield washer switch is pressed, battery voltage is applied through the switch contacts and the windshield washer switch signal circuit through the body control module (BCM) and to the windshield washer pump. The BCM monitors voltage on this circuit to detect when a WASH cycle is requested so it can enable the wipers. After a short delay, the BCM energizes the wiper ON/OFF relay which will operate the windshield wiper motor at low speed. The wiper motor will continue to operate for 2 wipe cycles after the wash switch is released.

MIST OPERATION
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, voltage is applied through a internal resistor and through the windshield wiper switch low signal circuit to the body control module (BCM). The BCM will then energize the wiper ON/OFF relay which will operate the windshield wiper motor at low speed until the switch is released.

INTERMITTENT OPERATION
Windshield wiper DELAY operation is a low speed wiper motor function with a variable delay interval between the wiper motor cycles. The DELAY interval is determined by a series of 5 resistors within the wiper/washer switch. During DELAY wiper operation the signal circuit voltage is further reduced through the DELAY resistors. The body control module (BCM) monitors the voltage on the wiper switch 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.

LOW SPEED OPERATION
When the wiper switch is in the LOW position, voltage is applied through an internal resistor and the wiper switch low signal circuit to the body control module (BCM). The BCM then applies voltage through the windshield wiper switch signal 2 circuit that energizes the wiper ON/OFF relay. This allows battery positive voltage from the WIPER fuse to flow through the ON/OFF and HI/LO relays to the wiper motor. The wiper motor will operate at low speed, since the wiper HI/LO relay is de-energized. Low speed can also be commanded with a scan tool, by commanding Wiper Relay Cmd. ON and OFF. Refer to Scan Tool Output Controls .

HIGH SPEED OPERATION
When the wiper switch is in the HIGH position, battery positive voltage is applied through both, the windshield wiper switch low signal circuit to the body control module (BCM), and the windshield wiper switch high signal circuit to the wiper HI/LO relay. The voltage from the windshield wiper switch high signal circuit energizes both, the wiper HI/LO relay, and through the wiper diode also energizes the ON/OFF relay. This allows battery positive voltage from the WIPER fuse to flow through the ON/OFF relay input, the switch contacts, and out to the input of the wiper HI/LO relay. Now with the wiper HI/LO relay energized and it's switch contacts closed to the wiper motor high speed circuit, the wiper motor will operate at high speed.

PARK POSITION OPERATION
Windshield wiper motor park operation is controlled by the body control module (BCM) using an input from the park switch that is located 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 glass or in the park position. During wiper operation and each time the wiper blades are at the bottom of the glass, the park switch is momentarily closed to ground signaling the BCM the wiper position. 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 turned ON.

The wipers will not park when they are commanded ON and OFF with a scan tool. The BCM will park the wipers the next time the wiper switch is turned ON and OFF.

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 operating, the BCM will assume that the wiper motor is stalled, and will de-energize the wiper relay until the wiper switch is cycled OFF and ON again.

WINDSHIELD WIPER/WASHER SYSTEM POWER AND GROUND
With the ignition in the ON position, accessory voltage is supplied through the 30A WIPER fuse to the ON/OFF relay and the WPR/WASHER 10A fuse in the underhood fuse block. Then from the WPR/WASHER fuse to the wiper/washer switch. Ground is provided to the windshield wiper motor through the wiper motor ground circuit and G201. Refer to Wiper/Washer System Schematics.