I have a 2011 e550. I've had it for about 4 years and have run it up to almost 140k miles. I love this car. I have had the issue with the sunroof not draining right. A little leakage here or there usually drips via the front windshield caught on the front rubber floor mat. Blew out the drain hoses from time to time and went along. About 2 months ago, after a massive tropical downpour, I had a lot of water. I mean A LOT of water. The front driver seat floor area got quite a bit on the rubber mat, but I was able to dry that fairly fast. The driver side rear seat, however, kept filling up with water draining from somewhere. It took me about 3 days to get things dry. I would be able to dry it until lightly moist and 2 hours later it was soaking wet again, over and over. I did not pull back the floor mats (mortal sin).

About 2 weeks later, after driving without any problems, I start the car and all the fault lights come on, warnings, etc. The car runs, but the engine fan runs high. I can shift, the car drives, but hardly anything control-wise works. No wipers, no indicator lights... The dashboard gauges (speed, rpm, fuel, clock, coolant temp) all work fine. From time to time all the warning lights go off, the outside temperature gauge comes on for a few seconds (normal state), and then it's back into mayhem. This flips back and forth and then after about 20 minutes running, the car behaves normally. At that point, all controls work, but the check engine light is on and the COMAND system stays switched off and says it will activate the anti-theft system (but that didn't happen). I have driven the car at that point for 30-45 minutes without an issue, just a dead COMAND and a check engine light.

We took the seats out and pulled the floor mats back. There was water around some parts of the cable bundles. Two smaller sensors got moisture too. We opened those and cleaned/dried them. We dried and sprayed everything with a moisture repellent while exposing everything to lots of dry warm air. Full inspection showed no corrosion or degradation of the wiring. We also checked and cleaned the front fuse box where old leaves had caused some leakage into it as well (that whole front drain system is a design fault in the tropics if you ask me), but no corrosion or anything major to see. We put it all back together. Fault codes cleared, but a week later exactly the same thing. We think it is very likely one of the SAM units but we cannot prove it. Exchanging them looks painful with no connectors and what appears to be all soldered wires.

Does anybody have any idea or suggestions for diagnosis? If it is the SAM, does anybody have any experience with the work (is it soldering?) or cost of replacement (labor and parts)? Hate to toss a perfectly good car because of this. I would really like to be able to fix it / get it fixed.

Thanks for your help, advice, and suggestions.

 

Funny you mention the sam. Mine caught on fire in the 500 wagon at my kids baseball game. Wipers turned on, smoke, car tried to start itself...it was great. I found a sam with about a foot of the wiring and soldered it in. Took about 2 hours. I thought there's no way this is going to end well. Fired up first try and it's been almost 2 years without issue. I'm still patting myself on the back for that one. If this is the route you end up with...do not skimp on the solder job. Use good wire, use good insulation.

The culprit in my situation was wiring in the SAM box was longer than it needed to be (in my opinion) and some of the wires had chafed pre fuse and welded themselves together. A little research found this to be an issue with some Sprinter Van's. Couldn't find much info on it happening in a MB car.

I think I paid $50 for a matching option sam from a 500 wagon off of ebay.

 

Every time you wash you car, use a leaf blower on the drain holes

 

Many thanks. It's at least encouraging. Does anybody know if there are multiple different models front and rear SAM's for an '11 e550, depending on features (a bit hard to imagine) or are they all the same? Likewise, is there a difference between the e350 SAM's end those for the e550 in a particular model year?

 

There are different options cars so the sam will either have deletes or inclusions. The one I found was an exact match. Not by any means saying this is your issue, but just in case it is. I have an E500 wagon 4matic so I started there. Found tons of Sam panels. Then I narrowed it down using supplied VIN #'s with the Sam's until I found the exact same package as I had. There were (if memory serves) 5 matches for mine. I chose the one with the best seller feedback.