Hi all, I've been experiencing some weird headlamp issues with my 2012 E550 Coupe, the symptoms are as follows:

1. Low beams work fine no matter how long I use them for

2. High beams both light up when triggered

3. Extended high beam use or toggling the high beams on and off eventually causes the right side headlamp to go out (both low beam and high beam stop working)

4. Once the right side headlight goes out, if I use the switch to turn off then on the headlights, the right side will come on for a split second before turning itself off

5. The right side headlight won't be usable until I restart the engine, at which point I can freely replicate the failure again.

6. The right side high beam, even when working, feels dim compared to the left side. it is only slightly brighter than the low beam whereas the left side is quite a bit brighter.
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What I've tried so far:
1. Switching the left and right bulbs, left to right vice versa - the issue still occurs on the right side

2. Replace the bulbs back to their original sides, and switching the ballasts/control modules attached to the headlight modules from the left to the right and vice versa. I paid close attention to make sure the connectors were fully inserted by pushing down on the male end from the inside of the headlamp module. The issue still occurs on the right side.

3. I pulled a bunch of fuses in the box, fuses 5, 18, 29, 30, none of which affected the headlights functioning, nor wer they burned in any visible way

Suspects:
1. bad relay? I don't know where the headlight relay is on the c207, if it even has a replaceable relay module to begin with, so any hints there would be much appreciated!

2. Bad SAM module, like an internal short tripping some kind of over current or over temperature protection that persists until the alarm is cleared during restart? the momentary flash on when the lights are turned on via switch seems telling that it is a safety mechanism kicking in.

Any help would be much appreciated! is the SAM replacement a complex process? My dad has a 2016 w212 that appears to use the same SAM module (visually identical fuse box layout is all I have to go by right now), so if it's not too much trouble I can do a switcheroo there and see if the problem goes away

Thanks in advance!!

 

Could be a wiring issue. 2011 and up were known to have issues with the wiring harnesss degrading over time. IIRc that section can be replaced. Give konigstiger on this forum a shout and your vin. He can pull the harness parts and id placement etc

Also, the SAM module may need coding to your car if you replace it or swap one in from another vehicle. Others can chime in on that if needed.

 

Thanks for the advice! I've actually narrowed it down a little I believe. I think it is most likely the shutter flap that adjusts range being stuck. When I trigger the high beam I can only see the bright spot cast on the wall by the bad side expand ever so slightly, unlike the good side which very obviously grows in size and projected height. That is unfortunate as these lamp modules run $900-1.3k.

Does anyone have a post about front bumper removal on the 2012 C207? I got have way but was met with some resistance so I chickened out and put things back in place while I still could. Or is there a way to remove the passenger side headlamp module without dropping the bumper?