2006 MB R350 4M

My 2006 R350 electrical system had a total upset this week. After starting up, the engine ran fine, but all warning and caution lights started to blink on and off. I heard the tail gate unlatch and latch again continuously, and exterior alarm lights were blinking. My sons called this “glitching". Quickly I switched off the engine and took key out, but still had warning and caution lights flashing. Alarm sounded occasionally, while locking and unlocking the doors worked only intermittent.

Called, then went to the local Mercedes garage. While driving, I noticed when I attempted to open the tailgate with the switch that’s in the driver’s door, the flashing of lights momentarily stopped and then started again. This interruption of flashing of lights and latching/unlatching of the tailgate got my attention and I mentioned it to the garage. Upon arrival the car battery was disconnected to avoid draining. I suspected something like chafing of wiring that had to do with the tailgate.

After a one hour investigating the problem, they found if they pulled a 40 amp (orange) circuit breaker from the rear fuse box (right of spare wheel, see attachment), the flashing of lights and continuous latching/unlatching stopped. All wiring that was related to the tailgate latching and tailgate motor was inspected and seemed to be undamaged. Putting the fuse back immediately caused blinking and you could hear the relays switch about every second.

Pulling the fuse solved the problem, but it created a new situation where some items don’t function anymore:
1. Tailgate motor doesn’t open/close anymore. Tailgate latches and can be manually opened.
2. Driver’s door, Passenger door and rear passenger left door can’t be locked or unlocked with the remote. Driver’s door can’t be locked or unlocked with key either (assume the key is not mechanically linked, but operates an electrical switch in the door)
3. Rear right passenger door and tail gate can be locked and unlocked with remote.

In general the car now runs without glitching, so we can use it again, but it’s impractical because the car can’t be locked. I can lock all doors from inside, then I can exit through the right aft passenger door and lock that door with the remote. Fortunately, the battery doesn’t drain when it’s locked. Returning back into the car requires an athletic maneuver to get behind the wheel after entering though the right aft passenger door.

https://mbworld.org/forums/images/smilies/crazy.gif

So, what to do now. Further online investigation by me led to nothing. I see lots of Mercedes tailgate issues on this MBworld forum, and it’s a know problem with the R-class. But most posts talk about the latching mechanism. Some have a burnt motor, but I haven’t seen this one yet. I checked all wiring I could find on the left side of the spare wheel, where the tailgate hydraulic motor and the tail gate controller are located. I pulled all wires from the controller one-by-one and checked it by inserting the fuse back in, but that doesn’t solve it.

Will normally pulling the 40 amp (orange) fuse from the rear fuse box result in the same situation? In other words, can this situation be duplicated with a normal functioning R350 by pulling the fuse? Who wants to check that for me?

Who knows more about the electrical system for further trouble shooting?

All ideas are appreciated.

2006 MB R350 4M

See attached video to hear and see how the latching mechanism operates.

This is what you see:
- At first I try to close it by pushing the lock mechanism with a screw driver. At first attempt it unlocks and it makes the weird sound for 3 seconds.
- Then I push it a second time and then I’m able to lock it.
- With the key remote, I unlock again

This weird rattling sound of the tailgate latch mechanism could be heard for the past years when opening/closing. It could be heard every time when opening with the remote key, as it moves slow. The sound would not be heard if you would open the tailgate manually, by pulling it open immediately after unlatching and pushing it firmly closed at the end of the automatic door travel. Seems like helping the latch mechanism helped.

The tailgate latch mechanism may be related to the electrical problem of the blinking lights, but I have to do more investigation to confirm that.

egorey

Did you ever determine what the cause of the "glitching" was? Our 2008 started this last evening (hazard lights / alarms / locks / tailgate latch) and following your suggestion (pulling fuse 40) was the only thing we could do to stop the fracas. Searching today, your experience seems to be the only other report that I can find. I have checked the fuses, wiring, pulled the SAM. I found some old water stains on the board in the SAM but nothing that looked recent. Cleaned the board and replaced the SAM, verified all connections, replaced the fuse and we went right back to the light show.

I realize it has been quite some time since you posted but hopefully a reply will spur a message. Thanks in advance for any help 2006 MB R350 4M.

2006 MB R350 4M

egorey,

I’m sorry to hear you have the same problem.

I have never found the source of the problem. We drove around with the fuse back in, but with the tail gate motor disconnected. This caused some door locks to be inoperable as well. Remarkably after a few months it looked like some of the door locks started to work again on the remote. Just by itself! That made all logistics easier again. Didn’t need to unlock/lock manually and climb over to the right rear door to get in/out of the car. But the tail gate was still unpowered.

The tail gate latch mechanism kept on rattling, unless a special technique was used. By engaging the switch in the handle, then quickly pulling the handle to open the tail gate, the rattling silenced quickly after opening. So only if you just hit the tailgate switch in the handle, but didn’t pull, the rattling would start. This is how we used the car for over another year. I don’t know if the rattling tail gate latch mechanism had anything to do with the “glitching” or the non-functioning door locks after disconnecting the tail gate motor.

Some people advised me to replace the aft switch board. I look at it, but it seemed fine. No burnt electronics, no signs of overheating somewhere. I looked only, but new boards were very expensive and I wouldn’t trust a used board as well. So I left the tail gate unlatch mechanisme rattly or use the technique, and accepted the tail gate to be manually open.

After another few months I had to replace the rear air bags. I always kept the engine running on the best synthetic oil, and had the service done by the local MB garage. But on Jan 1st of this year, the engine died. The car gave up. One cilinder (no5) completely lost its compression. It was probably caused by a valve that broke off when the engine revved up to climb a small slope in the road while on cruise control. Reading further in this forum, I believe it was due to a piece of plastic from the variable inlet flapper valve that may have become stuck between the valve, causing it to hit the cilinder head. Engine had run more than 200k miles. A head replacement would maybe have solved the problem, but maybe bigger issues could be discovered. Replacing the engine was more expensive than the value of the car. And since we had had so many troubles with the car before, it was time to say goodbye. No more high mile Mercedes in my garage. Too many things that can break. After 6 weeks searching for another car, I purchased a used 2008 GMS Acadia with 100k miles. The R350 was traded in for $500. I bought the car 2.5 years and 35k miles before for $9000. Quite a steep write-off.

I hope you find a solution for your “glitching” issue and have more confidence in your car to keep it.

ACEMAC

Did you ever figure out this problem? I have the exact same identical problem with mines any information will be greatly appreciated

2006 MB R350 4M

Unfortunately I never figured out the exact cause of the problem, although I suspected a faulty SAM. I just kept driving it with the pulled fuse, leaving me locking some doors manually whenever I parked the car in a public parking area, which was a pain, but workable.

A couple months later though, the engine broke itself. While driving on the freeway on cruise control when the terrain started to slope up, the engine shifted back from 6th, to 5th, then 4th gear and ran suddenly at 4000 rpm. The old engine was working as hard as it could, then suddenly all engine lights went on and I heard a horrible engine sound, lost 80% power and the engine was in safe mode, running unstable in idle.

The local Mercedes garage told me one of the cilinders had lost its compression and a head ($3000+) replacement was required, or maybe even a full engine replacement ($5000+). The theory of the cause was the plastic variable inlet. The plastic tends to become brittle over the years and a piece of plastic had broken off and had been sucked in the inlet, and coincidentally got stuck between the inlet valve and inlet seating. Therefore the inlet valve couldn’t fully close and the piston had knocked against the inlet valve, which had been bent/cracked by the piston.

The car looked beautiful, but it was trash. I couldn’t just get rid of it that easily, but after a couple months I just had to let it go. Received $500 discount on the new car I bought. Sad.

This Mercedes had been a pain in the @$$. I judged it by its looks, but under the hood is was a problem car. Lost $8000 in a heartbeat. Probably never buy a Mercedes again.