Hello there,


I'm hoping someone on here can provide some insight as to what I might do next and whether or not I've damaged my car in more way than one.

To give you some insight as to what happened, my AC isn't working. It flashes when pressed and then turns off, the compressor doesn't even turn on. I've already tried recharging it with an AC PRO Recharge kit with no luck so a mechanically inclined friend of mine helped me out and scanned my car with a Bluetooth dongle like thing (Blue something or another was its name) and there came up being no codes... which was unfortunate and left me (per his advice) with only the option of pulling all the fuses and hoping one of them was blown. (I tried looking at the diagram for the fuse layout in the driver's side dashboard fuse box, however, it is only useful for the trunk fusebox and the driver's side fuse box, not the engine bay. And also seems to be fitted for an older Mercedes based on the diagrams within it. So my friend and I pulled each fuse individually looking for anything, corrosion, a blown fuse, nothing. All the fuses are in working order (We didn't test them, but visually they appeared fine). 

The important part of this all is that in front of the driver's side fuse box, there is a large brown grounding wire that goes from the fuse box to the body via a screw and nut. We pulled that off and noticed some corrosion and cleaned it best we could (the car was off at this point and was throughout pulling all the fuses, no lights were on and the key was not in the ignition, we did not, however, remove the negative battery terminal.) Upon screwing the wire back to the frame via the nut and bolt it rests sandwiched between, we decided to clean the outside of the car but had some difficulty maneuvering the sunroof, the motion can best be described as jerky and unresponsive to many of the movements of the sunroof switch, only moving 50-60% of the time we tried to push the switch. We eventually got it closed, but haven't touched it since.

At that time we were confused but figured since we had had problems with the car's sunroof in the past it was simply the car being an old car. The next problems came after we had finished cleaning it and were about to drive off, we turned the car on and our dashboard lit up like a Christmas tree, with ABS and ESP lights and the circular screen in the center telling us there were faults in the ABS and ESP systems, and to visit a workshop. We were quite startled to find these lights as we didn't touch anything in those two systems except the fuses. 

In addition to these lights, power steering seems to be a bit funny and requires more than the usual amount of effort to turn.

Since then, we have let the car sit overnight and drove it briefly this morning only to find that the check engine light is now also on.


We are planning on taking the car to an AutoZone/Advanced Autoparts store to get the car scanned and see if any of the codes were because of "low battery voltages" or something of that nature since we did disconnect that rather thick and seemingly important grounding connection and did re-socket/check every single fuse in the car. I've done what little research I can and it seems the low voltage could bring on those lights. We won't fully know until later today.


What I'd like to ask is for any advice or help of any kind. I'm a fledgling of a mechanic if even that and this was the first time I've really gone fiddling with my car.


If you could help me get a handle for what I may have to do next and whether or not my car is actually broken in any of these ways I would be most appreciative.


Thank you for any replies!

- Hammy/Hamburger123598


Just finished reading your post. Sorry to hear about your troubles. I am glad you provided those details.

What you have done by removing all the fuses one by one, is that you have basically reset every system (module) on your car. While it is not recommended to pull the fuses, generally there is no damage casued by doing so. Except that you will have to resynchronize a few things. 

I will go over what you need to do.

  1. First start the car and turn the steering wheel from left to right a couple of times. Your BAS and ESP and other lights on the dashboard should turn off. If they don't, try turning the steering wheel all the way to the left (hold two seconds) then all the way to the right one more time. Holding it for two seconds when it reaches full turn left or right.
  2. Next is the sunroof. Your sunroof needs to be synchronized. Press the switch mutiple times until you get the sunroof to the back. When the sunroof reaches the back hold the switch pushed (as if you are still tyring to open) back for five seconds. Next, move the sunroof forward. It will take multiple times pressing the switch. When it is closed, keep the switch pressed forward five seconds. This will synchronize your sunroof. Note that if your sunroof was damaged, it may get stuck open. Very unlikly if you had a working sunroof to start with. Lubricate the sunroof rails with Liquid Wrench or similar if you can.
  3. Windows. You didn't mention or maybe test your windows. But the auto open or close feature does not work. Press and hold the switch for a few seconds in the full closed and fully opened position once the windo reaches those positions.
  4. A/C. Your A/C system need to be scanned with a scanner that can read codes from Mercedes AC control module. A generic scanner ( I think you may have used BlueDriver) can not access MB AC module. If there is a current code in the module the system will not work until that issue is addressed. There is not much you can do at this point, but find a mechanic that specialized on MB cars.

I hope I didn't miss somthing. :)

Thank you so much for the help! I was worried I'd be waiting endlessly for a response!


We originally tried turning the wheel back and forth to no avail after researching the issues yesterday. I will try holding the wheel there today.


As for the AC, can I buy a scanner specific to MB cars and use that? If so would retailers like Autozone and Advanced Autoparts have one?


I will most certainly try the things you mentioned for the ABS and ESP and Sunroof and look into getting a hold of a scanner to check the AC. (BTW, BlueDriver is in fact that OBDII scanner that was used, thank you for correcting me on that one)


Thanks for your help! 



Make sure the engien is running when you turn the steering wheel and hold it at full turn a couple of seconds. If that doesn't work, drive around  for a few minutes. That should take care of that ABS and other traction related warning lights.

The icarsoft sacnner can read the AC system on MB. Take a look at this article:  http://www.mercedesmedic.com/best-obd-2-can-scanners-for-car-diagnostics/

I haven't seen a good scanner at Advance or Autozone. Even the scanner that they have in stock are way over priced.


Just wanted to update this thread with a bit of a resolution. @MercedesMedic your tips were extremely useful and fixed everything (ABS & ESP lights went off soon after locking the wheel right and left for a few seconds each and then taking the car around the block for a second. Power steering was soon restored and we could switch between Sport and Comfort modes using the mode selector by the gear shaft (before we were unable to, it was stuck in sport)

The windows curiously enough worked fine but we did what you suggested anyways. The sunroof tends to get stuck in an open position anyways so we decided to just fiddle with the auto "up" and "down" vent-like motion of the sunroof, fixing that in a jiffy.

Last but not least was the Check Engine light. I believe part of that might have been because when we opened the hood yesterday, we found the fuse cover and the subsequent rubber snap-on paneling sitting in the middle of the engine. Our theory is that the fuse box cover was not secured properly and jostled loose while the car was being driven yesterday morning. Rest assured we replaced the cover and ensured it was properly sealed to the fusebox, and then reinstalled the rubber-like covering to protect that area.

After replacing those panels we drove to an AutoZone and had them scan our car and clear the codes that were present, all 18 of them (figures after we unintentionally reset literally everything). After scanning the car and viewing the codes and then viewing them while the car was running (a live update of the codes basically) they disappeared as did the check engine light!

Last but not least is the AC. Unfortunately, that as of early today still does not function, but my friend and I are going to try to "reset" it somehow (he found an article on resetting a Mercedes AC system, I have yet to see it so I can't necessarily provide any more details on it) 

If that doesn't work we will take the car to a garage specializing in MB and let them work on it, but we would much rather try to save ourselves the money and fix it ourselves. Sadly given we don't know what's wrong with it (I'm not sure I can justify the cost of an icar scanner for just this one issue) I'm not sure there's any hope in not taking it to a mechanic.


I'll keep this thread updated with more information as things develop.


Thank you for your help @MercedesMedic!

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