I'm having problems with my 2009 w204. No ac, no blinkers, brake light on, high beam light on, check engine on, no horn, srs light on. There has been water ingress in the cabin over the years.

I checked the front Sam -- absolutely no water ingress; circuit board and connectors look flawless.
Swapped 15r relay - issue persisted.

Cleaned the 3 can junction boxes to the left of the driver footwell because there was mild corrosion - issue went away during cleaning then returned days later. I think it was coincidence. I'm getting about 2.5v on each wire except one brown stripe one, which I'm assuming is a ground because it looks different than the others.

Are there any other can junctions in the interior that may be corroded? I'm really stumped here.

 

Hi
I would go back to the 3 junction boxes re-clean then and see if any difference can be detected.
have a really good look up inside all the terminals for corrosion when you are finished apply some dielectric grease.

 

I'm just going to replace them. Didn't realize they're only $10 each. I'm hoping this is the issue despite looking perfectly clean now

I was considering steering column, but that wouldn't explain the ac not working
I'm hoping it's not the front Sam, because I don't have the means to program that myself

 

Just a small update,

The distribution boxes fixed it. I took the old boxes apart for inspection, and I really didn't notice any more oxidation on them (they had been cleaned with deoxit), but they were still inoperable. So, if anyone is googling this issue -- although the distribution blocks may look clean and you have 2.5v on every wire, it's worth replacing them.

All fixed.

 

Happen to have the part numbers on those distribution blocks...for a 2009 C300, right ?

 

It is for a c63, so the part numbers may be different. I'd double check
004-546-76-40
004-546-81-40
004-546-82-40

 

Thanks.....Mercedespartswholesale. cross referenced those part numbers to a c300 also.

 

And to add to the Google keyword list, I also had intermittent issues with starting the car. It would not crank unless I tried 3-4 times. Lastly, I also had an intense vibration during idle while in gear (not P or N) when the car wasn't warmed up. These issues all resolved.

 

What do I Google search to buy distribution blocks ?

 

What are the part numbers for c300 please 🙏

 

Did you read the previous posts?

 

Since you're still experiencing issues despite your efforts, it's possible that there could be other corroded junctions lurking in the interior of the vehicle. It's essential to thoroughly inspect all potential areas of water ingress to identify and address any corrosion.
Considering the complexity of modern vehicle electrical systems, it might be beneficial to seek professional assistance. A qualified technician or a reputable NY Water Damage Restoration Company like alldryus.com can provide expert guidance and help diagnose the root cause of the issues you're experiencing.