Principles of Operation

Wipers and Washers

Principles of Operation

Windshield Wiper Operation

The wiper system is activated by the multifunction switch. The multifunction switch is mounted to the Steering Column Control Module (SCCM). The SCCM (Steering Column Control Module) commands the wiper motor to activate the appropriate wash, low, high and intermittent modes through a private Local Interconnect Network (LIN).

When the multifunction switch is in the HIGH position, the wiper motor also receives a ground signal which is hardwired directly through the SCCM (Steering Column Control Module) (bypassing the logic within the module). This fail-safe circuit makes sure that the wipers function in HIGH speed mode in the event of a LIN (Local Interconnect Network) communication failure.

Vehicles equipped with a front video camera have a front camera washer control switch that is part of the multifunction switch.

Washer System (if not equipped with front video camera)

When the multifunction switch is placed in the WASH position, the SCCM (Steering Column Control Module) sends the request to the windshield wiper motor through the LIN (Local Interconnect Network). The windshield wiper motor supplies voltage to the washer pump, which then directs washer fluid to the windshield.

Washer System (if equipped with front video camera)

When the multifunction switch is placed in the WASH position, the windshield wiper motor supplies voltage to the washer pump. Ground is provided to the washer pump through the normally closed contact in the front camera washer relay (located in the auxiliary Battery Junction Box (BJB) ).

When the front video camera washer control is activated, the SCCM (Steering Column Control Module) sends the request to the windshield wiper motor through the LIN (Local Interconnect Network). The windshield wiper motor controls the direction of the washer pump to direct washer fluid to the front video camera.

Courtesy Wipe Feature

When the washer system is activated, the wipers cycle 3 times with washer fluid, followed by one final wipe a few seconds later to clear any remaining fluid that is dripping from the top of the windshield. This feature can be enabled/disabled through the message center. For information on enabling/disabling this feature, refer to the Owner's Literature.

Speed Dependent Wipers

If equipped, the speed dependent feature increases the frequency of wiping to compensate for the extra moisture that accumulates on the windshield as the vehicle speed increases. This feature activates when the multifunction switch is in any intermittent setting except the INT 1 position. As vehicle speed increases, the speed dependent feature gradually shortens the delay between wipes. The SCCM (Steering Column Control Module) receives Vehicle Speed Sensor (VSS) information from the Body Control Module (BCM) through the High Speed Controller Area Network (HS-CAN). The SCCM (Steering Column Control Module) sends the VSS (Vehicle Speed Sensor) information to the wiper motor through the LIN (Local Interconnect Network).

Rain Sensitive Wipers (if equipped)

When equipped, the rain sensitive wiper feature replaces the intermittent wiper feature. The rain sensitive feature is active when the multifunction switch is in any of the 5 auto/intermittent sensitivity settings. The setting closest to OFF is the least sensitive to moisture, the highest setting being the most sensitive to moisture.

The rain sensor optically senses water on the windshield. An infrared beam of specific intensity lights a section of the windshield. The intensity of the reflected beam is measured and compared to the intensity of the transmitted beam. If there is water on the surface of the windshield, the beam distorts, reducing the intensity of the beam. If the beam is not reflected completely, it is interpreted as rain on the windshield and the windshield wipers are started.

The rain sensor sends data through the LIN (Local Interconnect Network) to the windshield wiper motor. When the rain sensitive wiper feature is enabled, based on the data received from the rain sensor and the auto/intermittent setting on the multifunction switch, the system automatically activates and adjusts the wiper speed and frequency when moisture is detected on the windshield.

A gel-type lens is used as the interface between the rain sensor and the windshield. If the lens is missing or damaged, the rain sensing wipers can be inoperative. The rain sensor gel-type lens is part of the rain sensor and cannot be replaced separately on a rain sensor of this type.

The rain sensitive wiper feature can be enabled/disabled through the message center.

When the rain sensitive wipers are disabled from the message center, or the windshield wiper motor detects a fault with the rain sensor input, the windshield wiper motor changes to a default intermittent mode. The timing of the wipers correspond to a standard intermittent setting based on the auto/intermittent sensitivity setting on the multifunction switch.

Wiper Activated Headlamps

If equipped with automatic headlamps, the SCCM (Steering Column Control Module) sends a message to the BCM (Body Control Module) over the HS-CAN (High Speed Controller Area Network) to illuminate the exterior lamps within 10 seconds of the wipers being activated by the multifunction switch when the headlamp control switch is in the AUTOLAMP position. The BCM (Body Control Module) continues to illuminate the exterior lamps for approximately 30 seconds after the wipers have been turned off.

If equipped with rain sensitive wipers (feature must be enabled through the message center) and the multifunction switch is in 1 of the 5 auto/intermittent settings, the SCCM (Steering Column Control Module) sends a message to the BCM (Body Control Module) over the HS-CAN (High Speed Controller Area Network) to illuminate the exterior lamps within 30 seconds of the wipers being activated by moisture detected on the windshield when the headlamp control switch is in the AUTOLAMP position. The BCM (Body Control Module) continues to illuminate the exterior lamps for approximately 60 seconds after the wipers have been deactivated (moisture no longer detected on the windshield).