mikey33

Hi Guys. I installed new bulbs in my car and they were working fine for about a month and then I went to change a bulb and accidentally touch a screw driver to the metal and all the bulbs instantly started blinking and going dim. I thought I blown a fuse, but every fuse in the car has been checked 100% and they all work. What is powering the interior and trunk lights and could it possibly be a relay since I am still getting 7.3v instead of 12? I know a fuse is either working or not, so that cancels out that solution I believe.

Thanks

AMGPilot

Fuse powers sam, sam powers bulb. Sounds like you blew an output stage in a sam

mikey33

Damn. How do I figure out or test to see which one is bad?

03'55AMG

Sam is in the trunk correct?

mikey33

Trunk and engine compartment.

mikey33

I know I have to replace one of the box's in the sam which is a relay, but which one I do not know.

I need a wiring diagram I guess.

mikey33

Update, I pulled every sam/relay module to see if they were working and they all are. The lights stayed on the whole time, but are not getting the full 12v, only 7.35v. This is a total mystery to me, are there any other fuses or modules in the car that I am missing? I checked the drivers side, trunk compartment, and engine compartment. I also opened up every other part of the car, but there were no other electrical boxes of any kind. Thanks!

mikey33

I have narrowed the issue to the prefuses now. Either in the trunk or under the footwell. Something in there is causing the sucker to go wacky, but it does not make sense why I have partial power if a fuse is blown, and it is not running through a sam.

mikey33

Here are the diagrams I am using to figure the problem out or this website for FREE DIAGRAMS!!!

http://www.mercedestechstore.com/w211.htm

mikey33

Okay guys I tore the trunk apart and tested the fuses by the battery and no freaking luck! I have no damn clue what the issue is or what is causing the loss of power to the four interior lights and trunk lights. They are steadily dim and about every five seconds flash up to their normal brightness (12v), but no clue what is causing the issue.

I couldn't find the prefuse box under the front passenger side footwell. Does anybody know where it is located? Thanks.

harjothundal

Does this happen with the car both on and off? Reason I ask, my alternator is starting to die and I'm getting dimming symptoms such as you stated.

mikey33

Hi. Yes it does do it when the car is on and off, but they were working fine before I touched the metal bracket with a flat tip screw driver which caused some sort of short. My dad is an electrical engineer and he cannot even figure it out after 3 hours tearing the car apart. He is saying there is no way it is a fuse, and has to be something else. What has us baffled is why their is still power, yet not full power. The roof lights, glove box, side mirror lights, rear view mirror lights, and sun visor lights all work fine still. There has to be something separate that are powering those lights, and trunk lights. I think the electrical in these cars are very complex and not understood very well by anybody from what I can see on these forums, but I am going to keep digging!

regor60

Seems like you blew something (open circuit) in parallel with the circuit, not series

mikey33

Bump for help please.

dyno

here's the pre-fuse and sam at the passenger's footwell


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don't know if it can help you.

trunk illumination is controlled by the rear sam

interior lights should be controlled by front sam ..

Hellzno

have you put the original size bulbs back in? When this happened did you smell any burning plastic smell? Could be a fried wire somewhere? Did you try taking the dimming bulbs out and then measure voltage? just suggestions. good luck

mikey33

Thanks for the reply's guys! I found the prefuses under the passenger footwell, but nothing much to test. I also did put the standard bulbs back I'm and they are also having the same issue of 7.3v only. I also removed the bulbs and tested the socket alone and it is receiving the same 7.3v. Something had to have blown, and anytime I have ever seen such an issue it was a simple fuse, but these cars ae obviously more intricate. Btw Dyno, do u know what fuse or module in the sam's to be looking at? I have tested them all by pulling them one by one to see if the lights go out, but with no luck Thanks

mikey33

Btw, no burnt smell or fried wires. Has to be something in the sam's that are causing the issue. The issue originally started when my flat tip touched the socket in the rear passenger light socket under the seat, where the feet go.

03'55AMG

I know it may sound nuts, but maybe try shorting it out again, because maybe It is in the SAM but it's not all the way blown. Or test all the fuses and modules resistance.. Maybe when you shorted it, it was not long enough to melt the strip in the fuse.. Just a suggestion

turbovan

The voltage is probably regulated by an IC or transistor circuit to provide variable intensity for the lighting. You probably damaged this part of the circuit. I don't think there will be an easy fix for this one

dyno

so, what bulbs exactly:
the bulb at each footwell + the bulb in the trunk ?

look to the right: footwell lamps are ocntrolled by Front SAM unde rthe hood (N10/1)


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dyno

system functioning


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dyno

as Voltage is not totally gone, I am wondering if it's just a matter of just simply resetting the dimming setting/brightness from the steering wheel ...

mikey33

Hi. Yeah it's the bulbs at each footwell in the front and rear, and the three trunk lights.

mikey33

I tried this but that only controls the overhead dome lights. Is there some other option I'm missing?