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Mercedes-Benz R-Class Electrical Problems



  • Hi James,
    Did you ever find out what was going on with your tail lights? My R500 does the same thing. Also my horn has gone out. I'd feel silly if I took it in and someone tightened one screw and charged me $300. I'd love to know what was done to fix it.

    Thanks! Don
  • Don

    Took the car to the local Benz dealer, they were kind enough to fix it free of charge, to me that's indication that they were having problems on many of the cars. If I understand the fix, it has something to do with the light socket making contact to the tail light housing, or lack of making contact. 50,000.00 miles seems to be the magic number, under that and they make a free fix. Spoke with another R350 owner that had the same problem with the tail lights. Can't help you with the horn problem. Hope this is of some help. Take care & travel safe
  • My car now has 110,000 Miles. OMG! Major problems.
    Replaced steering column
    tail lights kept burning out
    cruise control went out
    windshield wipers went out
    The car would cut off constantly
    Harnerss wiring issues

    They tried to blame me (coin in cigarette lighter).

    Most of my work was covered under warranty. They even paid me out some money. After the warranty ended. They want me to pay. They have had to replace the fuse box.....maybe about $5500.

    Major electrical issues.
  • Hopefully my post can be seen by ctdan.
    I have the same exact problems about not being able to shift gears. I just want to know if the ISM Motor replacement actually worked or not.

    I have a 2006 R350. It just started showing this problem intermittently and is very annoying.
  • ctdanctdan Posts: 23
    CTDan here - saw your post and the ISM replacement did fix the problem, although the dealer had it for over 2 weeks before the could figure out what the root cause/resolution was.

    Since then I have had numerous issues unrelated to the ISM, the last one being a leak in the sunroof that wasn't visible in the cabin of the car, but apparently channeled down into the battery compartment which is under one of the seats. This caused the battery to short out every few days. Another trip on the dreaded flatbed (4 in 2 years) for another 2+ week stay at the dealer where they couldn't figure out the problem. I guess I'm lucky all of these ridiculous repairs have been under warranty. Just very, very poor quality vehicle.
  • We own the R320 CDI, and while generally we really enjoy the vehicle it has quality issues that we've never experienced in vehicles half the price of this one.

    Case in point - the tail lights. Tail lights on both sides have failed repeatedly. This isn't a matter of the tail lights burning out. This appears to me to be a design flaw in the tail light assembly that relies on pressure point contact between the tail light casing and the bulb socket to conduct power to the light (as opposed to wiring that goes right into the bulb socket). Over time, it seems that the contacts on the bulb socket bend to a point that they no longer make contact with the metal on the tail light casing (which I believe is conducting the power). We've "fixed" these several times, only to have them fail again shortly after fixing. (Interestly, other lights in the assembly rely on this same design but have not failed.)

    Has anyone else experienced this on their R-Class. I assume so given what our local Mercedes mechanic tells us (and the knowing shaking of his head when we present the problem to him).

    Appreciate any feedback from other RClass owners.
  • Dear All,
    I am interested in buyiung an R350 4 Matic - should I or Not buy it?
  • depends of the year.
    Stay away of the 2006 and 2007
  • evemevem Posts: 2
    Hi there,
    Just wondering if you can share some more information. We just bought a R350 2008, just over 4 weeks ago. Whole host of issues, including replacing front light within 1st 2 weeks. Most recent issue, is leaking sun roof that penetrated in to floor of car casuing battery damage. MB are stating not under warranty and looking for 9K to repair which is absurd. Any further information regarding your similar situation with sunroof would be very appreciated.
  • evemevem Posts: 2
    Hi there,
    Just wondering if you can share some more information. We just bought a R350 2008, just over 4 weeks ago. Whole host of issues, including replacing front light within 1st 2 weeks. Most recent issue, is leaking sun roof that penetrated in to floor of car casuing battery damage. MB are stating not under warranty and looking for 9K to repair which is absurd. Any further information regarding your similar situation with sunroof would be very appreciated.
  • ctdanctdan Posts: 23
    How can they possibly claim that this is not under warranty?!? Tell your dealer to contact MB of Fairfield in CT and speak to John DeStefano, he was/is my svc advisor whom unfortunately I have gotten to know much better than I should have given all of the issues I've experienced over the past couple of years. If it has happened to me and you, I would bet there are others, and this is leaky sunroof/wet battery problem one of those "known issues" that they do no speak about externally.

    BTW my latest issue is that there is no longer any working audio... no radio, no sound from GPS, no ipod, etc.

    I am thankful that I replaced this lemon with a Volvo XC90 a few months back, which so far has been very positive. Doesn't ride as smoothly as the R Class, but at least everything works as designed. My R Class has been sitting in my driveway since there is no benefit for me to turn it in early.

    Good luck and please provide an update as to how it works out.
  • clynneclynne Posts: 1
    I have a R350 2007. I never had consistant problems other then the tail and front lights going out. I truly believe this is common with these vehicle. But once my warranty expired a couple of months ago, my Check Engine light has been on 3 times and the car seems like it's not going to stay on while it's running. Each tme I take it back they find that it has nothing to do with the previous problem (even though the symptoms are the same each time). I don't recall what the first diagnosis was, but the 2nd one was code 0703 Crank Sensor found faulty, the 3rd time they found code 0629 & 0633 which is some coil issues. Guess what today I'm having the same issue and the check engine light has returned. I'll be taking it in again the 4th time tomorrow and I'm sure they will find a few new codes to charge me for. Well I'm done.......I'm looking to trade this baby in.
  • Hey ctdan, are you still looking for help with your leaking sunroof/battery problem? I have an E320 that I experienced the same issue. There are drain tubes that run through both 'pillars' of the front windshield that drain the sunroof. In my case, these tubes became constricted with decomposed leaves. The draining water backed up but continued down the pillars, on to the floor, traveled almost undetected beneath the floor mats and found the lowest spot to collect - where the battery is located under the right side rear passengers seat. This is also the location of the main fuse box on my car. This cause numerous electrical gremlins! It's a good idea to run a piece of ridgid wire (co-ax cable) down these drain lines to keep them clear! :D
  • bautistabautista Posts: 1
    I got the same problem I have the 2006 R350 and it woun't shift gear, bad thing is, it's not under warranty anymore, can a local car repair fix this? How much MB dealer charge for this services like changing the ISM motor of the control unit. This is a headache!!!
  • ctdanctdan Posts: 23
    Hmm good question. Hopefully you have a local repair guy that you can trust. I do not know what MB charged since it was covered under warranty, but I cannot imagine it would be inexpensive. Good luck.

    BTW I finally turned my 2008 R350 back in when lease expired at the end of Feb. Good Riddance! I had replaced it with a 2011 Volvo XC90 which I have been driving for about 6 months & very satisfied with so far. Nothing spectacular, just solid, reliable, easy to drive, comfortable, no major drawbacks, overall a good value.
  • The best to fix it is REPLACING THE CAR!!!
    I changed it last November for a 2011 GLK350 Fantastic Ride and build like a tank, proudly made in Germany! absolutely no problem whatsoever.
    I lost money on the R350, they updated the software, and some other things but they could NEVER pinpoint the random shifting problems and shake ups.
    This adds up to alternator problems, early serpentine failure, battery failures, the panorama roof slowness, the random tailgate light problems, etc.
    And the last one before I traded in, the taildoor shocks were broken. Bill to fix those around a $1,000 that is when I decided to trade it in.

    Mercedes Benz dark ages of electrical problems between 2001 until 2007, especially the ones assembled in the USA.
    Finally in 2008 they increased the quality again.
    2006 R350 first batch of R350s it is like the Gremlins built those cars. I would stay away from them.
  • ccgwccgw Posts: 2
    I agree with the previous post.

    We got rid of our R350 (first year model) and we've been happy since! There were just too many electrical problems that it wasn't enjoyable car ownership with all these trips to the dealership for the annoying myriad of problems, mostly electrical.

    It's a shame as most Mercs do handle well, although my grip of the R350 besides being a bit underpowered for the weight, is the dim standards headlights (I couldn't get one with the HID lights with the one I bought at the time..)

    How are the GL's in terms of reliability and lack of trouble??? Test drove one and it was fine. How about the E350's??? Hadn't dared consider buying another Merc because of bad experience with our R350.
  • rcf8000rcf8000 Posts: 619
    I've had my 2011 GL450 for 3 months. I've had two significant problems so far, both electrical. The a/c intermittently quit supplying cold air, and the tailgate sometimes closes as desired but then opens, for no apparent reason. This has happened at least a half dozen times. I haven't gone to the dealer for the tailgate problem, but the a/c was fixed after several days in the shop. There have been a few other signs of electrical gremlins, too, but things that have occurred only once. My guess is that MB has not exorcised the electrical problems from these vehicles.
  • Hi There,

    I'm curious, what prompted the steering column replacement? I have a 2006 R350 and I'm starting to get a clicking and thumping that I can feel under the front floorboards when I make a turn. I'm trying to pinpoint the issue before taking it to my MB dealer. I'm glad I took out an extended warranty, I'm having lots of problems (I'm happy to post the list of issues if anyone is interested) including some possible transmission issues :( I love Mercedes but these issues combined with a lack of courtesy and friendliness at the dealership are making me wonder whether I'll ever buy another benz...


  • My R350 cut off while driving on the hwy, was able to pull off to the side. Turned car back on and it would't go into gear, drive or reverse.
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