Diagnosis?
Thread Starter
Junior Member
Joined: Nov 2019
Posts: 29
Likes: 3
2004 W211 E320 Wagon
Diagnosis?
Hi all
I’ve had an intermittent electrical problem for the last few months. While driving, all of a sudden, I’ll will notice i’ve had a intermittent electrical problem for the last few months. While driving, all of a sudden I notice that my indicators/wipers/lights/radio/SRS etc won’t work. As well, the electrical warning light comes on in the dash. Historically, if I pull over, remove the key, insert the key again and start again, everything comes back on, and it is if nothing had happened. However, now the problem is 100% there. The car starts fine, but none of these electrics work. I took it to Mercedes, and they said it was the battery control unit next to the main battery (had to order this as Mercedes doesn’t make it any more). I replaced this and the problem is still there. (There is a small chance that the control unit I purchased is faulty, but I doubt it, and for the sake of this message, I am assuming it works). I’m not particularly impressed with the Mercedes workshop here, but of course I can take it back to them, but before I do - Wondering if anyone has some ideas? Ignition unit fault? Thanks in advance!
I’ve had an intermittent electrical problem for the last few months. While driving, all of a sudden, I’ll will notice i’ve had a intermittent electrical problem for the last few months. While driving, all of a sudden I notice that my indicators/wipers/lights/radio/SRS etc won’t work. As well, the electrical warning light comes on in the dash. Historically, if I pull over, remove the key, insert the key again and start again, everything comes back on, and it is if nothing had happened. However, now the problem is 100% there. The car starts fine, but none of these electrics work. I took it to Mercedes, and they said it was the battery control unit next to the main battery (had to order this as Mercedes doesn’t make it any more). I replaced this and the problem is still there. (There is a small chance that the control unit I purchased is faulty, but I doubt it, and for the sake of this message, I am assuming it works). I’m not particularly impressed with the Mercedes workshop here, but of course I can take it back to them, but before I do - Wondering if anyone has some ideas? Ignition unit fault? Thanks in advance!
Last edited by ads1212; Apr 5, 2023 at 09:28 PM. Reason: Get rid of caps.
MBWorld Fanatic!
Joined: Feb 2014
Posts: 6,190
Likes: 1,550
From: MA
2008 E350 4Matic, 2011 E350 4matic
Well it is a W211 so you can display the voltage on the dash. Switch to the temperature display and hit the reset button 3 times without the engine running but with the key in the on position. If there's nothing wrong with the battery control module, then it's either the alternator or battery. You should be able to figure it out from the battery voltage display. It disables convenience items when voltage is below 11. If it's the alternator, make sure you look up right part number in EPC as there's a few different alternators that can fit the pre-facelifted models.
MBWorld Fanatic!
Joined: Feb 2014
Posts: 6,190
Likes: 1,550
From: MA
2008 E350 4Matic, 2011 E350 4matic
