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Mercedes-Benz R-Class Electrical Problems

PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 9,226
Have an electircal problem with your vehicle? This is the place to work it out.

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  • mejomejo Posts: 2
    Has anyone has any electrical problems with their R350? I have the Saks Fifth Avenue edition and the tail gate motor burned out last week and now the battery light and brake light have come on. The service department said they do not know what the problem is and want to drive it for a while. I traded my ML for this beautiful car last November because of a lot of problems with it. I don't think the dealership is particularly excited to see us again.
  • nomorebenznomorebenz Posts: 109
    My tailgate had to be reprogrammed. Works ok now. I have only about 2K miles. No other notable electrical issues other than sensitive anti-pinch mechanisims in the rear quarter windows during the winter.
  • albellalbell Posts: 185
    I believe there are one or more service bulletins out on the tail gate issue, so you are not alone. I am 10,000 miles in and no real issues.
  • benzsterbenzster Posts: 152
    No problems with mine either.
    I have seen a vehicle with this issue. The bullitin states adjust latch/ do not replace. We tried to adjust 4 times and ended up installing a new latch to remedy........
  • ccgwccgw Posts: 2
    I do have problems with the rear left taillight. The bulb burnt out prematurely with dark metal vapor on the inside of the bulb. So, I tested the power supply with the good bulb from the right. The bulb did not light up (although I have noticed before I found the browned out bulb that the light would either be dark or slowly come on with a dull glow from time to time when I was following the R350). Took it to the dealer and they said it was a bad bulb and replaced it. Several months afterwards the same thing happened with no light from that rear red light. Something weird that I also noticed was the yellow light at the left coming on sporadically. Took it to the dealer and they had to order a new socket (?) WHICH IS ON BACK-ORDER!!! It has been over a month and they still don't have it. I think it is risky to drive the car with a bad red taillight, not to mention risk of getting a ticket? Does anyone know of such issues with the light? What action can or should I take?
  • koolkat1koolkat1 Posts: 1
    We had a dvd player that crapped out and the battery keeps draining. The dealer has had the car for over a week and they have no idea why this is happening.
    And come to think of it, the hatch doesn't always close properly.
  • We bought our brand new 2008 R350 this month. 2 days after driving away, the battery drained completely (car would not even open with key). The technician chalked it up to one of two things: 1.) the kids leaving a light on, even though our kids can't reach the upper light & do not touch anything else. (we are especially careful to check for lights on at night, especially because of kids/school etc). or 2.) the battery was not charged fully at delivery, due vehicle sitting in dealer lot for winter months (we are in New England). This morning i had 2 super important appts & a game w/ the kids, The car battery is dead again. The vehicle has 428 miles on it! It died at 205 & now 400+ miles. I purchased it with 170 miles on it brand new.. what is going on with Mercedes?

    I love the way the car drives, and kids love the space, but i gave up my old Merc wagon for the R350 not just because the kids love it.. but becasue of R-E-L-I-A-B-I-L-I-T-Y. I can't explain this so far & when the technician came prompty this morning (same person as first time), he couldn't either. Told me definitely there was something unnecessarily draining the battery and this was/is very odd.. i have to take it in for service now for them to diagnose The car is 12 days old!. Do i have a lemon? (gosh hope not because i love the interior, the drive etc), but this is unacceptable.. Will see what the dealer says & does..
  • lcjdlcjd Posts: 2
    We are having the same problem. We bought our 2008 R350 in Dec07 with 5700 miles. At 9700 miles, the battery was completely drained and the car was towed to the dealer. They had it for 9 days, then returned it (with hesitancy) saying they still didn't know what caused it and it would probably happen again. They did replace the battery. Well, it did happen again at 13,500 miles, it was towed back to the dealer and they kept the car for 2 days. They wanted to keep it longer, but we said we needed it back. Now, at 14K, it was towed back to the dealer for the 3rd time with a completely drained battery. They called today to say MB told them to replace a control unit(?) and the part would be in in 2 days. We also have some problems with the clocks in the car. They don't keep accurate time a few days before the car battery is drained.

    Like you, we love the car. It drives great, has so much space and the kids love having their friends ride with them. I don't see us keeping it once the warrenty expires unless this problem is diagnosed!
  • nicky2244nicky2244 Posts: 1
    Have a 2006 R-350 with about 13500 miles. Car won't start, changed battery all the lights cut on but the car still won't start. Jump it off and finally Now a red battery light cut on saying I need to take my car to the dealership. My car is in the garage now tomorrow I have to call Mercedes and waist another day of electrical problems. This is a 2006 why won't my car start. I check my car remote batteries, replaced them. Still won't start. I should have waited and bought the 2006 GMC Acadia. Has anyone have anything happen like this let me know. I might just trade it in on the GMC. Never had a problem with a gmc never and i still have one gmc Denila
  • Well, i have a bit of good news to report. About 3+ weeks ago the dealership got tired of servicing our car (read my previous message on this forum). Also the lemon law kicked in as it had been there for 14 days. The service dept could not figure out how a new car with 450 odd miles on it was being drained/ would not start after a full charge evry couple days. Told me car has 3+ miles of wiring & rather than tinker with it, they replaced our 'old' R350 with a brand new one with 9 miles on it. Exact same with identical package & they threw in the Xenon lighting as a courtesy for all the trouble. They will be sending the old one back to Mercedes in Alabama to lok at. Been driving our new car close to a month now & it is a dream.. the reason we bought this yacht in the first place. Well, that's our story so far. I hope Benz can resolve the wiring/battery issues in future models to alleviate trouble some of us have been experiencing. All the best.
  • caliberchiccaliberchic Posts: 402
    Congrats on the replacement!! :)
  • soundermnsoundermn Posts: 2
    We've got 18k miles on the car. Lease is up next month and it's going back. Electrical problems we've had:
    - electric tailgate fail, adjusted twice.
    - rear windows stopped working.
    - SRS red warning light. Dealer replaced airbag module. Light is on again, six months later
    - battery light comes on periodically. Dealer has fixed it three times, and its on again now
    - low antifreeze light comes on periodically. Dealer has fixed it twice, it's fine now.
    - installed tow package, and it took the dealer 7.5 hours to connect the harness. After discount, it cost me $500 to install the wiring harness (which is the same as ML harness)
    - non-xenon headlights. Had to return to dealer twice to adjust headlight aim

    All these are minor problems, and were fixed without question, and without drama at the dealer. However, for a car that cost $60,000 with tax, I should not have to take it back to the dealer every three months for some other goofy problem. We aren't happy owners. Yes, its comfortable, drives great, looks good. But, it's big, can be hard to park, and has to visit the dealer far too often.
  • ctdanctdan Posts: 38
    I've had my 2008 R350 for a few months and it has just over 5k miles, until a few days ago everything was great. Within the last week or so the check engine light has come on and stayed on. Not that big of a deal in and of itself, but then oddly the outside temperature display on the dash started jumping up and down randomly. Two days ago I watched it go from +8 to -4 to +185 all in the span of about 5 minutes. Then when I filled up the tank from 1/4 full and the needle on the gas gauge did not move from 1/4 to full position for about 30 minutes, I thought maybe the tank had a leak or something was wrong with the pump. On top of all of that the key fob remote has become very unreliable - but only with one of the key fobs??

    Independently I would not be too worried, but collectively all of these happening within a few days of each other gives me some concern. Took it to the deal this morning and of course the check engine light is no longer illuminated, the temp gauge seemed to be working normally and haven't filled up the tank again. Just had a call from the MB Svc Mgr and he told me they had were able to diagnose some of the issues and replace a few sensors, that should take care of the check engine light & external temp readings and he was going to send the car home with a tech and fill up the tank to see if they could reproduce the fuel level reading. If he can then they would have to take out the gas tank and then replace some additional sensors for that as well.

    I am hoping that all of these are not representative of a larger issue...any thoughts?
  • I have 06 R 350, at times the tail lights don't light and I get a read out " left substitute light on" other times it will be " right substitute light on" and sometimes I get a readout that both "left & right substitute light on" will be displayed. Running lights never light. Could it be the head light switch? Car has 50,000 K
  • ctdanctdan Posts: 38
    My post from 11/10 listed some minor problems which were "fixed" by replacing a few sensors, now a week later it looks like I am now in the club of the low voltage, power drain. When I went out to the car yesterday morning there was a constant beeping with a message on the dash saying something to the effect of "return to workshop, do not put in gear". When I put the key in, the car started sluggishly (low power) and then starting with all sorts of flashing waring lights. Also oddly the wipers went on by themselves - although they were in the off position. The car would not go into gear, either fwd or reverse. Called the dealer, they dispatched a tow truck to bring my R350 back to the svc dept. Not a good feeling watching a 2008 that was a few months old being hauled out on a flatbed.

    The dealer told me that there were too many codes coming up to clearly identify the source of the problem, but they did isolate the fact that underlying issue was low voltage. They initially replaced the battery and ran some overnight diagnostics to check the battery drain in the morning. This morning they told me that there is definitely a drain coming from somewhere, but not sure of primary source. They think it may be coming from the fuel pump since my last gas gauge issue identified in my 11/10 post. I find it interesting though that last week that was nothing to worry about and now they think it is the cause of the problem.

    After reading some of the other posts I do not get a level of comfort that they will be able to isolate and fix this issue as clearly there seems to be some kind of MB mfg default with no known resolution.

    Has anyone that has experienced this low voltage/electrical problem been supplied with an actual resolution, other then a new vehicle?
  • lcjdlcjd Posts: 2
    MB replaced our steering control unit 7 months ago and ,knock on wood, it seems to have resolved our battery drain issue. Make sure the steering control unit is from a previous year, though. Not a 2008.

    I agree, watching the flatbed tow our 2008 - 3 times!- was no fun!
  • ctdanctdan Posts: 38
    Thanks for the response lcjd.

    Interesting, my dealer never mentioned a steering control unit as a potential problem. What he did tell me though when I my car was dropped off yesterday with this low voltage issue is that he had another R350 in the shop w/a similar problem.
  • ctdanctdan Posts: 38
    Just had an update from my Svc Tech and he confirmed that they found the source of the problem and it is the ISM Motor of the Control Unit.

    A quick google of "MB ISM Motor" revealed the exact same problem resulting in the “DRIVE DIRECTLY TO GARAGE WITHOUT CHANGING GEAR” message that I received.

    They told me that basically what happened is that the ISM Motor is defective - this is the part that controls the paddle to shift from park to drive & reverse. The faulty ISM was preventing the car from shifting gears, hence the message above about driving without changing gears (a physical impossibility, but let's not split hairs). The drain came from the fact that problem with the ISM Motor prevented the car from recognizing that it was in park and therefore resulted in the repeated beeping and the dome light to be illuminated with no way to shut either off - causing the battery to drain.

    He is replacing the ISM Motor tomorrow, hopefully that will do the trick. I'll post an update if it worked... or didn't.
  • I'm from Australia and this is my first post - I have a 2006 R350 which I purchased 7 months ago from a Mercedes Benz dealer. It is a 6 seater with "touring pack" which means that it has the removable console in between the 2nd row seats. I love the car, it has a couple of very annoying electrical bugs - thankfully not the battery draining issues that I have read about elsewhere on this forum. Firstly the 1 touch auto close on the sunroof doesn't work. When I use this feature the roof almost closes the reverses to a half open position. If I touch the button again it will then close fully. It will also close fully if I hold the button or if I use the key fob from outside the vehicle. So far the dealer has replace the wind deflector and the control module but the fault persists, the dealer is now saying that the rails may be warped and wants to changeover the entire sunroof cassette. Anyone else experienced this problem?
    Secondly, the auto light switch appears to have a mind of its own, sometimes turning the headlights on in the middle of the day in bright sunlight or refusing to turn the lights on at dusk or in low light conditions such as very heavy rain. The dealer has replaced the optical sensor but the fault persists.
    Finally, the front parking sensors seem to go crazy on hot days often emitting continuous tone and full led signal for several minutes for no apparent reason. This only affects the righthand side of the vehicle. Dealer says he cannot duplicate the problem.
    I would very much appreciate any advice or information regarding these annoying faults which spoil an otherwise excellent vehicle.
  • watkinstwatkinst Posts: 119
    Looking at 08 Rclass CDI's - anyone with the CDI 08 experiencing these issues? Guessing its all the same stuff just a different engine
  • 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: 38
    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.
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