Where is the rain sensor? 1999 SL500

[skybound]

I got caught in some light rain about 3 months back and tried the intermittant wiper feature on my 99 SL500, but the wiper never stopped, so I had to turn the wiper on and off again, quite annoying. I do not drive the car in the rain as a rule but would like to fix this problem myself if possible in case I need it again someday. I just do not have any clue as where to look for the sensor that controls the wipers. I searched on this board with no luck. Can anyone tell me where this sensor is????

[5280BENZ]

The sensor appears to be located on the windshield, in front of the rear-view mirror.

"

The rain sensor (B38) senses moisture on the windshield. When the combination switch (S4) is in the interval position the rain sensor (B38) controls the interval time.
When the combination switch (S4) is switched on or when power is switched to terminal 15R when the combination switch (S4) is already in the interval position, the wipers are actuated one time, even when the windshield is dry.

The rain sensor (B38) is connected to the multi-function control module (N10) or to the combination relay (N10/2) by a serial data bus. The multi-function control module (N10) or the combination relay (N10/2) sends a request to the rain sensor (B38) via the data bus. The rain sensor (B38) answers each request. The moisture on the windshield is measured by an optical element operating with infrared light. If the windshield in the area of the rain sensor (B38) is dry the light is reflected completely. If the windshield is wet in the area of the reflection surface the light is dispersed. The percentage of light reflected decreases as the moisture increases. This light reflection serves as the variable for control of the interval. If the rain sensor (B38) recognizes that the window is "moist", the multi-function control unit (N10) or the combination relay (N10/2) actuates the wiper motor (M6/1)."

[skybound]

Wow, I didn't realize the sensor was so intricate as system. Any idea as what to check first as to why it isn't working correctly? Maybe I should take it to a MB tech that knows this system.

[5280BENZ]

Originally Posted by skybound

Wow, I didn't realize the sensor was so intricate as system. Any idea as what to check first as to why it isn't working correctly? Maybe I should take it to a MB tech that knows this system.

Rather than throwing parts at the problem your suggestion re. a MB tech is the way i'd go.

[ScottinSoCal]

Originally Posted by 5280BENZ

Rather than throwing parts at the problem your suggestion re. a MB tech is the way i'd go.

I agree, but I'd bet it's going to be the infrared emitter. They have a tendency to get weak over time, and its output has probably dropped below the level that indicates a wet windshield.

[skybound]

Well, like I said before, this is too big and technical of a prob for me to tackle myself I think and will have it looked at by a MB tech for sure. Thanks for all the responses.