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Rain and Light Sensor Replacement
 
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Pelican Technical Article:

Rain and Light Sensor Replacement

Steve Vernon

Time:

30 minutes30 mins

Tab:

$60

Talent:

*

Tools:

Small flathead screwdriver, trim removal tool

Applicable Models:

Mercedes-Benz C250 (2012-14)
Mercedes-Benz C300 (2008-14)
Mercedes-Benz C350 (2008-14)
Mercedes-Benz GLK350 (2010-14)

Parts Required:

Sensor

Hot Tip:

Be careful working around the windshield

Performance Gain:

Working rain and low light sensor

Complementary Modification:

New wiper blades

If your Mercedes has the rain/light sensor for the windshield wipers and it starts acting up, changing out the sensor is quick and easy. The sensor is attached to the front windshield and can be replaced without removing the windshield.

The sensor determines rain by sending an infrared light from the transmitter in the sensor up into the windshield. If the windshield is clear almost all of the light will be reflected back to the sensor. If there is rain on the windshield then some of the light will be refracted and spread by the rain drops and cause a low light signal back to the sensor. The more rain the more light that gets dispersed. The low light is measured directly by the amount of light intensity falling on the sensor.

Start by shutting off the car and removing the key from the ignition.

The sensor is located under a plastic protective cover behind the rear view mirror and attached to the windshield (red arrow).
Figure 1

The sensor is located under a plastic protective cover behind the rear view mirror and attached to the windshield (red arrow).

Use a trim removal tool and gently pry the cover off the mount attached to the windshield (red arrow).
Figure 2

Use a trim removal tool and gently pry the cover off the mount attached to the windshield (red arrow).

This photo illustrates the plastic mount the cover is attached to (red arrows).
Figure 3

This photo illustrates the plastic mount the cover is attached to (red arrows).

Use a small flathead screwdriver and release the plastic tab (red arrow) and pull the wiring connection from the sensor.
Figure 4

Use a small flathead screwdriver and release the plastic tab (red arrow) and pull the wiring connection from the sensor.

Using the small flathead screwdriver very carefully pry the two clips out (red arrow, one shown) that hold the sensor to the windshield.
Figure 5

Using the small flathead screwdriver very carefully pry the two clips out (red arrow, one shown) that hold the sensor to the windshield. Gently remove the sensor.

This photo illustrates the windshield with the sensor removed so you can see what parts remain mounted to the glass (red arrow).
Figure 6

This photo illustrates the windshield with the sensor removed so you can see what parts remain mounted to the glass (red arrow).

The two metal clips on the sensor are delicate (red arrows) so use care when removing and installing them.
Figure 7

The two metal clips on the sensor are delicate (red arrows) so use care when removing and installing them. Installation is the reverse of removal.

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Comments and Suggestions:
Maurice Comments: i replaced the sumload sensor as it had an internal malfunction. I cleared the code, the warning still comes up on the dash. Now it says that the sun load sensor has a malfunction and that calibration was not performed. How do i calibrate it?
October 20, 2017
Sam Comments: Hi,
I have 2013 MB C250 Coupe. The car is showing "auto lamp function inoperative". The only problem it has is that there is no backlight on the audio system and steering wheel. Wiper blades are working fine. Is it the problem in the light sensor? The manual of MB says that the error message is related to faulty light sensor. And where do I find the light sensor on your website?

Thanks for your help!
August 9, 2017
  Followup from the Pelican Staff: Could be the ambient light sensor. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
M Comments: Hi, any luck on this blue circular mount part number requested below and if it can be ordered from Pelican?
November 4, 2016
  Followup from the Pelican Staff: Give the parts specialists a call. - Nick at Pelican Parts  
M Comments: On figure 6, one of the tabs are broken on the blue circular mount for a CLS W218 and the rain sensor will not attach. Can this circular mount be replaced from the windshield? What is the part number?
October 29, 2016
  Followup from the Pelican Staff:

I’m not the best with part numbers.


Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
dave Comments: Hi guys. Dave here I'm I bit of a situation my Mercedes c280's Eis.the cost has knock that in the head. If possible do have a ignition color code starter switch. Better would be to know what each wire does??? I've got a push button switch to replace the eis Any help would be greatly appreciated Yours truly Dave
October 18, 2016
  Followup from the Pelican Staff: You will need a wiring diagram, I don't have one to share. I would grab a repair manual, it will have it. - Nick at Pelican Parts  
Cullen Comments: Hello,
Wondering if you have a Rain and light sensor for an 2008 Mercedes C63 AMG. Can't seem to find this on your site, I can only find how to replace the piece of equipment.
Thanks
David
August 3, 2016
  Followup from the Pelican Staff: Pelican can get it.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Mauricio Comments: On my car the wipers dont work at all the headlights are always on if they are in automatic and the stereo doesnt dim at night do you guys think its the rain sensor?
July 30, 2016
  Followup from the Pelican Staff: Sounds more like a fault in a control module. I would start by checking the vehicle for fault codes. If multiple systems are not working properly, fault codes will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
 
nismo Comments: I have this the same problem now Auto Lamp Function Inoperative ..thought about replacing it too ..

wiper only works when you turn it on middle speed and turn on the car but it won't shut off until you turn off the car too.
any suggestion ?
June 28, 2016
  Followup from the Pelican Staff: What vehicle are you working on? SOunds like en electrical issue, not a rain sensor issue. - Nick at Pelican Parts  
Antonio Rizkallah Comments: i changed the sensor with a new one from Mercedes.
I still have the same problem : the lights always on and the message : Auto Lamp function inoperative.
what you suggest to do ??
May 31, 2016
  Followup from the Pelican Staff: Check the vehicle for fault codes to see what part has malfunctioned. - Nick at Pelican Parts  

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Page last updated: Sat 10/21/2017 02:59:56 AM