Grand Cherokee 2WD V6-3.7L (2008)
Ambient Light Sensor: Description and Operation
Description
DESCRIPTION
The Rain Sensor Module (RSM) (4) is the primary component of the automatic wiper system. In vehicles equipped with the automatic wiper system and
the automatic headlamp system, the RSM also performs the ambient light sensor function; and, therefore, is sometimes referred to as the Rain/Light
Sensor Module (RLSM). The RSM is located on the inside of the windshield just below the inside rear view mirror mounting button. The RSM is
concealed from view within the vehicle interior by a cavity in the top of the housing for the SmartBeam(R) camera on the rear view mirror bracket, but is
visible through the windshield glass from the exterior of the vehicle. See: Headlamp
The molded black plastic sensor housing has an integral connector receptacle (5) at the top containing four terminal pins. These terminal pins connect the
rain sensor to the vehicle electrical system through a dedicated take out and connector of the overhead wire harness that extends from above the
headliner. Openings on the windshield side of the housing are fitted with eight convex clear plastic lenses. A sliding cam lock retainer (3) on each side of
the sensor housing latches the sensor to four pins (2) on the mounting bracket (1), which is permanently bonded to the inside of the windshield glass with
an adhesive pad.
Concealed and protected within the sensor housing is the electronic circuitry of the module, which includes four InfraRed (IR) diodes, four photocells,
and a microprocessor. The sensor communicates with other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. The
rain sensor software is Flash compatible, which means it can be reprogrammed using Flash reprogramming procedures.
The rain sensor software is Flash compatible, which means it can be reprogrammed using Flash reprogramming procedures. The hardware of the sensor
cannot be adjusted or repaired. If ineffective or damaged, the entire module must be replaced. The RSM mounting bracket is serviced only as a unit with
the windshield glass.
