Principles Of Operation

Wipers and Washers

Principles of Operation

Windshield Wiper Operation

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

When the wiper/washer switch is in the HIGH position, the windshield wiper motor also receives ground 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 windshield wipers function in HIGH speed mode in the event of a LIN (Local Interconnect Network) communication failure.

Rear Window Wiper Operation

When the wiper/washer switch is in the INT 1 or INT 2 position, the SCCM (Steering Column Control Module) sends the request to the windshield wiper motor through the LIN (Local Interconnect Network). When the request is received, the windshield wiper motor supplies a momentary ground to the rear window wiper motor. The position of the wiper/washer switch determines the frequency of this ground. When the ground is present, it activates an integral relay within the rear window wiper motor which activates the motor. The rear window wiper motor is self parking.

Washer System

When the wiper/washer 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 controls the direction of the washer pump to direct washer fluid to the windshield or rear window.

Speed Dependent Wipers (if equipped)

When the wiper/washer switch is in any intermittent setting except the INT 1 position, the speed-dependent feature increases the frequency of wiping to compensate for the extra moisture that accumulates on the windshield as the vehicle's speed increases. 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 windshield 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 wiper/washer 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 wiper/washer 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 wiper/washer switch.

Wiper Activated Headlamps (if equipped)

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 windshield wipers being activated by the wiper/washer 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 windshield wipers have been turned off.

If equipped with rain sensitive wipers (feature must be enabled through the message center) and the wiper/washer switch is in one 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 windshield 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 windshield wipers have been deactivated (moisture no longer detected on the windshield).