Description And Operation: Description
An automatic wiper system is an available option. The vehicle may be equipped with a rain detection sensor on the windshield. When rain/water is detected on the windshield, the system will automatically operate the wipers. The system uses an infrared sensor fitted behind the windshield in front of the interior rear view mirror. The sensor continuously sends infrared rays against the windshield to detect the presence of water on the glass; if detected the sensor will send a signal on the Local Interface Network (LIN) data bus to the Body Control Module (BCM), which will activate the wiper at the appropriate speed.
The rain sensor is built into an electronic module Light Rain Sensor Module (LRSM) which, in addition to detecting moisture on the windshield, enables the dusk function by measuring ambient light levels. According to this information and the sensitivity level set by the user, it controls both windshield cleaning and running lights.
The LRSM (1) is the primary component of the automatic wiper system. The LRSM is also capable of performing an ambient light sensor function. The LRSM is located on the inside of the windshield glass just below and to the right of the inside rear view mirror mounting button. The LRSM is concealed from view within the vehicle interior by a molded plastic inside rear view mirror bracket trim cover that fits over the top of the LRSM housing and the LRSM mounting bracket, but the LRSM is visible through the windshield glass from the exterior of the vehicle.
The molded black plastic LRSM housing has an integral connector receptacle (2) with three terminal pins. These terminal pins connect the LRSM to the vehicle electrical system through a dedicated take out and connector of the overhead wire harness that extends from above the headliner. The windshield side of the housing is filled with a clear, silicone gelatin (also known as SilGel) adhesive membrane pad (3), which serves as an optical coupler between the sensor and the inside of the windshield glass. A spring steel retaining strap or clip extends forward on each side of the housing to latch the LRSM to a molded black plastic mounting bracket, which is permanently bonded to the inside of the windshield glass.
Concealed and protected within the LRSM housing is the electronic circuitry of the module, which includes an InfraRed (IR) diode and photocell based light and rain sensors, control electronics and LIN data bus communication management hardware. The LRSM is a LIN slave node and communicates over a single LIN bus circuit with the BCM. The BCM is a LIN master node and a gateway to the Controller Area Network (CAN) data bus. The BCM controls the exchange of electronic messages back and forth between the LRSM and other electronic modules in the vehicle, as well as with a diagnostic scan tool connected to the Data Link Connector (DLC).
The LRSM cannot be adjusted or repaired. If ineffective or damaged, the entire module must be replaced. The silicone gelatin adhesive membrane pad is available for separate service replacement. The LRSM mounting bracket is serviced only as a unit with the windshield glass.