Electrical issues
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Newbie
Joined: May 2025
Posts: 3
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2010 Mercedes C300
Electrical issues
I left the lights on one day and had a guy give me a jump. He took the cables up to the wrong terminals, and now the car runs, but the seats don’t move the radio doesn’t work. The sunroof doesn’t work. The left turning signal in the rear doesn’t work. I ran a couple diagnostics and cleared the codes, but it says there was not enough power to one of the modules, but I checked all the fuses and continuity and all the modules, and I am lost with where to go from there. I found several different wiring diagrams. I think it’s possibly an ECM board, but I don’t know how to check them or where to look. Should I just replace all the ECM boards? Could somebody help me please?
Joined: Nov 2016
Posts: 7,847
Likes: 3,493
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Do you mean he connected "+" to "-"?
You said you scanned and cleared codes. What scanner did you use?
You said you scanned and cleared codes. What scanner did you use?
Joined: Nov 2016
Posts: 7,847
Likes: 3,493
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Joined: Nov 2016
Posts: 7,847
Likes: 3,493
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Here's your problem: Mercedes are very temperamental when it comes to electronicsWhen that guy hooked up the batteries incorrectly, there is no telling what damage he did. You want to get a Mercedes-specific scanner and scan your car. The generic stuff, no matter how good the brand, is a waste of time with these cars. Ideally, you want a copy of XENTRY. Otherwise, the LAUNCH Creader Elite 2.0 BENZ is an excellent choice. You need a Mercedes-specific scanner to interrogate all the modules. Replacing all the damaged modules can be very expensive and time-consumming.
If you decide to stay with Mercedes, you will eventually get XENTRY. When you do, the BenzNinja Club is a good choice.
If you decide to stay with Mercedes, you will eventually get XENTRY. When you do, the BenzNinja Club is a good choice.
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Joined: Aug 2023
Posts: 3,576
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From: MA Coast
W204 2010 C300 4matic Sport M272
I would double check all the fuses again. I use this website for the fuse locations. https://fuse-box.info/mercedes-benz/...oogle_vignette
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Joined: Nov 2016
Posts: 7,847
Likes: 3,493
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
To Tim's point, checking the fuses again is a good idea. Many modules are "on" all the time, so turning the car off will not reset a module that is acting confused and that may be what you need to do. How did you check the fuses? Did you remove each fuse? You may want to do a chassis reset. Search for the term for postings by @CaliBenzDriver .
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Out Of Control!!
Joined: Apr 2019
Posts: 11,794
Likes: 6,700
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
JUMPERS CROSSED AROUND
BATTERY JUMPED BACKWARDS...
order your LAUNCH scanner on Amazon now
then try chassis Reboot
but 90% chance something got toasted.
Let's add things up to guess :
A good scanner will help you figure what's missing.
> Back to square one: JUMP
Why was your car out of power??
Have you recharged your batteries ??
What's draining power ?
order your LAUNCH scanner on Amazon now
then try chassis Reboot
but 90% chance something got toasted.
Let's add things up to guess :
- Seats don't move
- Rear lights don't work
- Radio headunit
- Sunroof stopped
- ....
A good scanner will help you figure what's missing.
> Back to square one: JUMP
Why was your car out of power??
Have you recharged your batteries ??
What's draining power ?
Last edited by CaliBenzDriver; May 14, 2025 at 01:10 PM.
