is there any way to test your seat control modules to see if they are draining your battery other than just unplugging them one at a time and seeing if they drain your battery?

Multi-meter...

Is the light sensor problem solved??

Was an old thread, but I was the original person that started this thread - if I remember correctly, it was a weak battery causing the "light sensor error" to appear. The cause of that weak battery was the passenger power seat module that was constantly draining the battery. Ended up replacing the seat module and everything was fine.

bnz616, Thanks!!

I have that problem now!
My w203 have a light sensor error and my battery is very weak..
But what does the passenger power seat module do?
Do I have one too?
I have a MB W203 from 2002

sorry for my poor English, I'm from the Netherlands

regards,
Michael

I believe the module controls the power seats (movement - forward, backward, up, down, etc). The modules are mounted to the underside of the two front seats. The module is probably black in color and has a wire harness (or a few) plugged to it, I would check but I no longer own a C-Class. I'm sure you have those under the seat. I took my car into a shop to have the module replaced, it wasn't cheap - $400-500 USD. Do a Google search for "W203 seat module battery drain", should return lots of info.

Some others on the forum have tried unplugging the harnesses to test if that was the cause of the battery drain. I'm not sure if that affects any safety aspects, so please research before doing so.

Even before you touch the seats though, you may want to just check the battery itself. It may just be as simple as being time to replace the battery to a new one. Weak batteries have been known to set off random sensors and warnings - other ones I've seen were traction control warnings, ABS warnings, etc.

I get the same error now "Light Sensor Visit Workshop", my headlight ( lowbeam) turn on even tho i set the switch in park, interior dome light does not work, and the left licence plate error pops up, but works after 5 secounds. any1 know how to fix this problem? do i need an new sensor?

Did you read the thread?

Even I went through this entire thread as it will surely help for later as back up knowledge. Anyone know how you would know the seat module is taking power apart from testing the battery when the car is off? I randomly hear my seat module making a ticking like operation noise that it would make when you engage the buttons to adjust the seat. But is has a pause inbetween and continues doing so. I am sure it goes off after doing something with the seat but its like that often and thank the Lord I don't have any battery issues though in the beginning I had that tail lamp plate error which I repaired with a new bulb. I haven't had issues since thank the Lord.

hey guys, today I took my 2007 c230 to the uphostery to change the headliner, as I drove away the light sensor workshop came on, can any one tell me how to fix that problem.

k

Hi I received the same message on my C230. I popped off the cover of the sensor just under the rear view mirror. It was very easy to see that there was a wire unplugged. I plugged it in and Wallah. Five-minute job

I had C230 had an error that said light sensor out drive to shop. After a little research I popped the cover off just under or behind rear view mirror. I found that there was a wire unplugged. I plugged it in it works just perfect. By the way I am not a mechanic

I bought this 2003 C180 used about 2 years ago and love this car but I must sell it and I really need to know that I've fixed the issue before I hand it over to someone else.

In the chill of the fall of the first year, I started to have the same intermittent "Light Sensor" error. IF it appeared, it was after I hadn't driven it for at least 8-10 hours. I saw it most often when it was cold and/or damp outside. The error would often clear itself, or after a quick ignition off then restart. Everything on the car always appears to work just fine except for the error messages. I am bothered when things don't work exactly right, so I took it to the shop right away, and they said the battery could be overcharging and recommended I change the battery even though it was only 3y old. The advice didn't sound right, but I did as they suggested but it didn't fix it. With everything functioning well except the warning, I kept driving it trying to figure out some pattern that would help me isolate the problem. The weather warmed up the issue nearly went away completely - I only saw the light sensor error msg about every 2-3 months.

Now that it's cold again, it is happening much more frequently, and it also is often associated with second a bright red screen indicating an electrical problem. I ran an ODBII check and found nothing. The new battery only has a few months on it. The shop already did an alternator and battery test and they can't find anything.

I thought I was onto something when I would make sure that the wipers, and especially the HVAC fan was off when I started it. I thought this because I noticed that it would start just fine, idle and if the error kicked in, the radio would go silent and the HVAC fan would stop. I tried this trick and it completed the engine warm up without error, until I went to drive a way, turned on the heater and got the error. The symptoms usually only last 2-3 seconds and then go away. I don't have power seats. Checked the condition of the wires in the rear view mirror connector box. The shop said that they checked my battery and voltage regulator. I'm at a loss. Is there a place I can go in order to find a proper troubleshooting guide for this symptom?

I'm having the same problem cat get stuck in first gear can't shift to 1234 .light sensor warning coming up checked battery voltage is a 11.9 I hope a new battery will solve my problem.
Thanks will try the swap for new battery