Hi all!
I'm a newbie here and a newbie to Mercedes Benz cars.
We recently purchased a really nice 2004 C320 4 Matic.
We can't figure out why the interior (dome) lights won't come on when we open the doors. The dome light works fine with the manual switch on the ceiling console near the light. All of the illuminated buttons light up when we open any door, but no dome light. The dome light switch has three posistions and we tried them all. Is there something that has to be programmed in the steering wheel computer controls?
I don't know if this is related: When we turn the headlamp switch to "auto" nothing happens. No headlamps at night. I can't get the headlamp delayor interior delay to work either.
The headlamps only work with the headlamp switch turned all the way to the "on" posistion or if we have the daytime running lights option enabled.
Do I have a bad sensor?
Thanks,
Joe

 

hi so when you put the headlight switch in auto no lights turn on at night? from the symptoms you described it does sound like a bad light sensor. on windshield behind rearview mirror.

 

Thanks for the response!
Yes, that is correct. No lights at night when switching to "auto" headlamps. And all the other things I mentioned seem to point to a bad sensor.
Does the interior light depend on the light sensor? That is, will it only come on when it's dark out?
And how about the delayed headlamps? Are they also dependant on the sensor?
Thanks,
Joe

 

I did a search here for "light sensor" and came up with a couple of posts.
From those posts I would think that if my sensor was bad, that I would get an error message on the dash stating so.
What do you think?
Thanks again,
Joe

 

hey. you will not get a message in the cluster. I have never seen that at the dealer ever. maybe you can try to unplug the sensor? maybe that will do something. or pull a fuse for it maybe. maybe the car is version coded incorrectly. its hard to say without diag at dealer. sorry dont know what else to say.

 

Thanks for responding! What exactly did you mean when you said "maybe the car is version coded incorrectly"? Please explain. Is that something I can check and correct myself?
Do these cars have the OBD2 diagnostics as my American cars have? If so where is the port? I do have the scanner.
By the way, the car is still under warranty,maybe I shouldjust go to the dealer. I have this paranoia about going to any dealers If you know what I mean... I usually check for error codes first before a visit to them. :-)

 

I dont blame you for not wanting to go to the dealer, Benz tries to make it hard for people to work on by themselves. version coding is coding that is specific for car options such as for the instrument cluster and the ignition switch, and front sam and rear sam these all have coding that can be changed to fit certain cars and options and sometimes when a new part at the dealer gets replaced things need to be reversion coded and sometimes things are missed. there is alot of coding that is stored in control modules. sometimes one little coding can be set wrong and it can cause all types of issues with the car. the OB2 is under driver side dash, right nearthe hood relaese handle.

 

OK, I think I fixed the problem(s)!
I failed to mention that the wipers didn't work on the auto mode either.
I unplugged and reconnected the rain/light sensor and now the auto wipers work (it's raining out!). However, it's not dark out yet to see if this corrected the lighting problems also. I will post back to let everyone know how I make out.
For future reference in case others have similar problems, here's what I did:
The rain/light sensor is mounted on the inside of the windshield behind the rear view mirror. I pulled off the black plastic cover exposing the sensor. I pulled off the small wiring connector (just pulled it off, no clips to press or pull) which immediately gave me a malfunction on the dash display. Then I plugged it back in, turned the car off, then back on. The malfunction was cleared and it seems this has "reset" the sensor.
Hope this helps others in the future!

 

OK, final reply on this subject!
All problems are fixed! Interior lights go on whena door is opened (at night), automatic headlamps now work (at night), time delay headlamps work, time delay interior lights work, and automatic rain sensor wipers work.
All cured from resetting the rain/light sensor! (as described in my last reply)
Hope this helps others too!
Thanks to all who helped!
Joe