Rain Sensor: Description

Fig 1: Rain Sensor

Courtesy of DAIMLERCHRYSLER CORP.

The rain sensor provides the primary input for the optional automatic wiper system. See Fig 1. The rain sensor is located on the inside of the windshield, where it is concealed within the molded plastic trim cover that snaps over the base of the rear view mirror arm. The sensor fits within the center of a ring-like molded plastic bracket that is glued to the inside of the windshield glass and that also serves as the support for the rear view mirror.

The rain sensor is contained within a circular molded black plastic housing with a short pigtail wire and a connector insulator containing three terminal cavities that exits one side of the housing. This pigtail connects 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. A molded plastic trough routes and conceals the pigtail wires on the inside of the windshield between the rear view mirror base and the headliner.

The windshield side of the rain sensor housing is open, but covered with a clear gelatin-like material that protects the internal electronic sensor circuitry and serves as the lens for the Infrared (IR) diodes and photocells within the sensor housing. This gel coating must never be touched or the rain sensor function may be impaired and the unit rendered unusable. The rain sensor cannot be adjusted or repaired and, if damaged or faulty, the entire sensor must be replaced. The sensor bracket and a rear view mirror adhesive kit are available for separate service replacement.