Mercedes Forum - Mercedes Benz Enthusiast Forums

Started with a flat battery last week. Not sure what caused battery to die, it is only two months old, so have ruled out needing a replacement.

Roadside assistance jumped car and it was dead again the next AM. Totally dead, jump wouldn't start it, we had to put it on charger for a couple of hours to get it to start. Roadside guy suggested that seat control modules might be culprit, so after charging, we disconnected both of them. Car sat for two days, but started fine when we next tried, so we set out to determine which module was kaput. Plugged in passenger side unit, and deemed it OK, because after car sat for two days with it connected, it started fine.

When we hooked up driver side to test, noticed that seat moved opposite from direction switch on door was pushed - seemed odd, vertical movement of seat, and seatback controls were normal. When we removed key, the seat wanted to move all the way forward instead of all the way back as it's supposed to. Left driver side plugged in overnight - passenger side was disconnected - and car started fine the next AM. Plugged passenger side back in, and it too was moving opposite direction from switch push.

At the same time, we notice that interior lights only sporadically coming on when the car is remotely unlocked, or the doors opened. Sometimes they work, sometimes they don't.

This AM, after having both seat modules plugged in overnight, car had enough juice to unlock doors, interior lights came on, but just a click from the solenoid when we tried to start. This time we were able to jump with our little truck and get car started.

Rain sensor has been an ongoing issue since it was replaced, with the light sensor about two months ago. Wondering if thelight sensor on the windshield has any involvement with the interior lighting or if it is only for the headlights when in the auto position, or if either sensor could be causing the battery drain.

Someone on another forum suggested the front SAM, but I'm not able to find much info on where it is, or what it does.

Wondering too, if there are things which might simply require reprogramming since the battery was totally dead for a few days while we waited out the weatheruntil the Roadside Assist guy could get to our house.

Do I likely have a couple of different, unrelated problems, or is there some module or controller that oversees both the seat, lighting and rain sensor electrics?

Thanks!

DFS