System Operation
Wipers and Washers - Front
System Operation
System Diagram
Network Message Chart
Module Network Input Messages - BCM (Body Control Module)
Windshield Wiper Operation
The windshield wiper/washer system is ready for operation when the ignition is ON. The SASM (Steering Angle Sensor Module) measures a voltage drop across the wiper/washer switch based on the wiper/washer switch position (OFF, LOW, HIGH or 1 of the 5 auto/intermittent positions). The SASM (Steering Angle Sensor Module) sends a message to the BCM (Body Control Module) over a LIN (Local Interconnect Network) based on the measured voltage drop. The BCM (Body Control Module) then sends a command to the LH (Left Hand) (driver side) wiper motor, over a separate LIN (Local Interconnect Network), which shares this message with the RH (Right Hand) (passenger side) wiper motor over a private communication circuit. The wiper motors respond by operating in the selected mode; low speed, high speed or 1 of the 5 auto/intermittent settings.
When the wiper/washer switch is in the HIGH position, the BCM (Body Control Module) also receives a signal which is hardwired directly from the SASM (Steering Angle Sensor Module). This fail-safe circuit makes sure that the windshield wipers will function in HIGH speed mode in the event of a LIN (Local Interconnect Network) failure between the BCM (Body Control Module) and the SASM (Steering Angle Sensor Module).
Wiper Activated Headlamps
If equipped with automatic headlamps, the BCM (Body Control Module) illuminates 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 BCM (Body Control Module) illuminates 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).
Speed Dependent Wipers
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 wiper/washer 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.
Rain Sensitive Wipers
The rain sensitive wiper feature takes the place of the conventional intermittent wiper system, but uses the same 5 position switch as the conventional intermittent system. To activate the rain sensitive wipers, position the wiper/washer switch to one of the 5 auto/intermittent settings. The auto/intermittent position closest to OFF is the least sensitive to moisture. The highest auto/intermittent position is the most sensitive to moisture. When the rain sensitive wiper system is active, the rain sensor optically senses water on the windshield by focusing an infrared beam of specific intensity on a section of the windshield. The beam is reflected back to a photocell receptor in the rain sensor. 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. This reduction of intensity is interpreted as rain on the windshield and the rain sensor sends a message to the BCM (Body Control Module) over a private LIN (Local Interconnect Network). The BCM (Body Control Module) then relays this message to the wiper motors over a private LIN (Local Interconnect Network) to activate the windshield wipers.
If the rain sensitive wiper system is disabled due to a system failure, the conventional intermittent wiper operation will be available for use by the driver.
Washer System
When the windshield washer switch is activated, the BCM (Body Control Module) receives a washer request from the SASM (Steering Angle Sensor Module) over a private LIN (Local Interconnect Network). The BCM (Body Control Module) activates the front washer relay, sending voltage to the washer pump motor. The washer pump motor then uses the rear washer relay as a pass through to ground. The front washer relay is located inside the BCM (Body Control Module) and cannot be serviced separately from the BCM (Body Control Module).
Courtesy Wipe
When the windshield 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.