Door lock is out of sync after replacing the battery

Tiny
DBOWMAN2
  • MEMBER
  • 2013 MERCEDES BENZ ML350
  • 6 CYL
  • TURBO
  • 4WD
  • AUTOMATIC
  • 101,000 MILES
Hello. After I replaced the battery in my vehicle listed above Bluetec (W166), the driver's side door lock went out of sync with the rest of the doors/hatch. Doesn't matter if I use the fob or either of the interior lock/unlock buttons - or if I manually set all the doors in the same position - as soon as I hit lock/unlock on the fob or switch the driver's door does the opposite of the lock or unlock button I've hit. I've read somewhere that this is a sign that a fuse has blown. After reading all the fuse/pre-fuse diagrams, the only fuse I can find that has anything to do with the driver's door is #253 in the f32/4 pre-fuse box. I cannot for the life of me find that box as I look around under the passenger seat and in the battery box. Hopefully, I don't have to remove the battery to access it - since that's what started this in the first place. Thanks for any help you can provide. Doug Bowman - Charlotte, NC.
Monday, December 27th, 2021 AT 8:20 AM

5 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,517 POSTS
Looking at the wiring there is only one fuse to power the door module, because the door is operating that fuse can't be the issue, if it were blown the door locks wouldn't work at all.
It sounds more like a data bus issue that will take an OE level scan tool to read the door module and see if it shows any errors. Then clear the errors and re-initialize the door module. Being a Mercedes, most aftermarket scan tools won't access the door module, so you need the OE unit. Looking at the way it is set up, once the fault is cleared it should initialize and work properly.
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Monday, December 27th, 2021 AT 2:02 PM
Tiny
DBOWMAN2
  • MEMBER
  • 3 POSTS
Thanks for the reply. I saw a few posts on MB blogs from people who had the exact symptoms and they said they replaced a fuse. The only fuse number I could find was on a W164 and it was fuse #42 (which I believe was a central locking fuse). Mine is a W166. For what it’s worth they said it fixed the problem and they were surprised that the locks would move at all with a blown fuse. I will find an import repair shop to get them to look for and reset codes. Any chance it might be worth a try to simply take off a battery lead for a minute or so and put it back on as a means to reboot again?
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Tuesday, December 28th, 2021 AT 9:51 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,517 POSTS
On another make I would say it's worth a try, but Mercedes can get really upset when you disconnect the battery, some will trip the antitheft, so they need to be towed in. The only fuse that feeds that door is fuse 253, the other two fuses show power to the left rear door module and the gas cap cover.
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Wednesday, December 29th, 2021 AT 10:28 AM
Tiny
DBOWMAN2
  • MEMBER
  • 3 POSTS
Okay. Thanks so much for the advice! I’m going to take it in and get myself out of the loop.
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Wednesday, December 29th, 2021 AT 11:28 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,517 POSTS
Let us know what they end up doing to correct it please. Mercedes can be interesting to deal with due to all the "extra" technology they like to add to the vehicles.
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Wednesday, December 29th, 2021 AT 8:08 PM

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