Electrical problem 02 ML500
 

Hi all,

I'm having electrical issues that the dealer is incapable of fixing.

It is intermittent. The windshield wipers stop functioning. While they are non functioning, I noticed that the garage door opener buttons also have lost power, and the the switched 12 volts outlet (front and back cigarette lighters) are non functional.

Dealer has replaced some windshield wiper switch at the base of the stoke on the driving wheel, as we were lucky enough to have the problem happen while the car was at the dealership.

We got stranded in the rain away from home and had to wait for a couple hours because the repairs they had done had not addressed the pblm.

I checked the fuse box to see if the three systems (wipers, door opener and swithced cig lighters) were on the same fuse and the fuse was lose or smthg, but no.

SHould not there be some kind of electrical schematic the dealer could look to see where htese three systems interesect to help diagnose the issue?

Has anyone had that wierd problem?

Thanks

Have you received a "recall" for a voltage regulator up-date..too high OR too low charging voltage can cause those problems..

No recall of the sort...
 

Thanks for your reply.

I have not received the recall you mentoin, and I am the original owner :(

I will mention this when I call the dealership later today.

At this point, the SA has requested all my keys, they changed the AAM.

I just hope this is fixed soon, I'd like to be able to use the ML on wet pavement, for high occupancy. That's kinda what I bought it for...

Thanks again for your reply MB Doc :)

SK

Here's a copy:

http://www.alldata.com/tsb/Mercedes-Benz/1144306800000_1145257200000_2005070017D/index.html

Thanks
 

Thank you for taking the time to post that information. :)

Should this be part of the solution, I am most troubled by the fact that the TSB describes that the low state of charge of the battery may prevent convenience features from functionning. I get the garage door opener, and the cig. lighters. I just thought that windshield wipers had made it past the "convenient" feature :laugh2:, last week, I found them critical safety devices in a downpour. I guess there's always Rain-X, but I hate that stuff.:rolleyes:

Thanks again!

SK

Follow up
 

This is an odd ball incident it seems, but should it help anyone...

Wolfgang, the TSB you referenced above was performed by the dealer, thanks for the info however!

The AAM was changed, and the problem has not occured since. Should the problem resurface and a solution be found, I will post it here for reference, just in case someone might derive benefit from that info.

Thanks again for the contributions. :)

It it helps anyone else...
 

The problem has re-occured. The AAM is, hence, not the answer.

I live to take trips to the dealership! :(

I would have guessed the fusebox (the part the fuses plug in to) before the AAM in this case. Unless i could get the failure to occur, in which case you test the systems, not guess. I have replaced a few ML wiper motors also, but that wouldn't explain the other failures.
Gilly

Thanks
 

Thank you Gilly. The ML is at the dealer still. They've had the issue in the shop, but are still unable to trace the culprit. The foreman mentioned the fusebox, but quickly dismissed it without checking I believe.

Another clue, the SRS and airbag lights come on every once in a while. The computer indicatesa problem with a sensor in the passenger seat for the child seat. They've replaced the part 3 times :rolleyes:, but it fails to resolve this. There does not seem to have a correlation with the wiper issue, but the electrical system seems to be at fault somehow.

Forgot to mention that prior to the wipers dying, a few months ago, they would sometimes react very slowly in the first few seconds of the wiping motion, and then would be fine. Only the first wipe.

I feel like -> :silly:
Sometimes like -> :behead:

But never like -> :idea2:

Would be easy thing to check fusebox, if anything is in a failed state anyways, that's the tough part. If they have a hard failure, they can just take up the fusebox and gently twist it to see if they can get a restart. On the sensor in the seat, they shoul dstart by checking voltage going to the sensor, comes direct from fusebox (unfused circuit IIRC).
Also I've heard MLs are developing a nasty habit of having bad ignition switches.
Gilly

FYI - If it can help someone
 

Finally, this issue was recently fixed...

If you have the same symptoms, a faulty ignition switch caused all these malfunctions.

I allowed the MB tech to use the ML for his personal transportation for an unrelated issue, and he diagnosed this electrical issue properly, better late...

On the subject, and hoping someone can benefit from this, the ML was in for another problem when this was fixed. It would jolt when shifting in R or D, and while driving, all five lights on the left of the cluster, plus the red brake light on the right would come on, at the same time (including the beeping), the transmission would stop shifting. If it happened from a stop, you'd be stuck in 1st gear, if it happened while driving, stuck in whichever gear it was in at the time of failure.

The transmission's computer was changed, but still the same failure occurred on my way home from picking the ML. Finally, a bad ESP module replaced fixed the issue.

Hope this helps someone, somewhere, and saves them the headaches of going back and forth to the dealership.

I'll get P/N when I get a chance to review the work order.