Hi all,

I am new to this, great forums btw!

I own a C63 w204 .. which is bloody amazing! unfortunately I drove through a rather big puddle of water (didn't realise how deep it was). I am now having electric issues.. it started going abit crazy.. first couple of days it wud shut of command randomly and turn on straight away .. after that I noticed it started doing it to the climate control.. again on and off etc... ... On the way to the garage the next day it was fine... (8miles away to book it in) but on the way back it jus went mental on me where even the indicators won't work and the wiper goin on and off randomly too... headlight and handbrake light keep flashing on dash...took it to the garage he said all the modules where ok and that he dried them out... But also mentioned that he had to drain the chassis for water...so brought it back home and now it won't even unlock in one press.. and when u out the key in it says inoperative.. see manual.. won't lock until I have to unplug the battery for 5 mins and it locks..

Anyone have any suggestions on what I can do please 😓😓💔.. love that thing so much ... Been drivin my other car an Audi TT vr6 07 .. good too but not as bad as the beast.. so again I would really appreciate any info.

Don't drive into lakes / rivers. I'm just imagining how deep this "puddle" must of been in order to affect your car. Try putting the car in a bag of rice for a couple of hours.

With respect, it would seem the depth of this puddle either was extremely deep or deep enough where water was sprayed over all the electronics, relays included. Water in the chassis? I'm not sure if there is water in the chassis frame how it would affect all the electronics of the car. Based on your description of issues, I'd suspect you may have just totaled your car.

How deep was the river you were fording?

As the alternator is mounted low, & the regulator is part of the alternator, I suspect it may be worth swapping the alternator for one that is known to be working fine.
I had a client experience similar random electrical issues & it was cured with a new alternator (& also new battery in his case).

^This. Those are symptoms of a failing alternator/regulator. I'd start there and hope for the best.

Test the alternator output voltage, and also for A/C ripple. Only a fool would just replace it without first testing.

I suggested swapping it with a known "good" unit - not buying new. In my experience, bench-testing modules that exhibit random behaviour can be misleading.

I'm sure the OP has a spare alternator laying around.:-). Real professionals don't operate that way. If the alternator is working correctly, you can check the UB voltage from the drivers seat.
It was taken to a repair shop, where I would think battery, and charging voltage was checked. AC ripple test is for diode health. Take it to a quality Mercedes shop.