W220 2002 S430 Electrical Diagnostics Help

[H2oPtics]

I'm not a mechanic, but I deal with low voltage at work, and two mechanics have already refused to touch this car, so here I am.

My parents gave me a half-wrecked 2002 S430 with a fantastic engine. They mentioned a few electrical issues over the last year, but couldn't get an exact timeline of events or if they even happened.

Main issues that came up when I got the car:

Rear suspension wouldn't lift (the mechanic replaced the shocks and some valve for the air suspension that he said was bad, in hindsight I'm pretty sure it was either just that valve or maybe something electrical and the mechanic stole it along with the shocks and valve for $1200, fun times).
Odometer completely non-functional.
Radio completely non-functional.
Trunk release from driver's door doesn't work.
Last issue that came up after I had the car for 1 week (battery completely died overnight when I put in a new battery).

1. The first thing I did was check the fuses of course and found nothing wrong with them.
2. I started looking for odometer issues and found that many people were saying that the capacitor on these models was failing, so I took it apart and checked it and it was fine (wasn't smart enough to find what kind of power supply I needed to check if it worked on its own outside the car or if that was even possible).
3. Once the battery started to go dead and no mechanic wanted to check it, I started looking for parasites and this is where I need help diagnosing my results, hopefully!

Found a fully submerged amp in the trunk (unplugged and put away for now).
Initial draw test after that gave me 3 amps, then the thing in the trunk that draws 7-8 amps died (after about 30 seconds).
Found 3 fuses that draw about 2.5 amps total.

1- Fuse 23 in the left engine bay - draws 1.2 amps (10 amp fuse - climate control/AAC control and operation/circulation pump/left dual valve/right dual valve) - this is what I found on that fuse, wondering if anyone has any info on what exactly to do to stop this draw? The AC works phenomenally, if you must know, it doesn't just work well, it may work too well.
2- Fuse 13 in the left engine bay - draws about 5 amps (40 amp fuse - left front door control module). Does it just need to be replaced?
3- Fuse 39 in the right engine bay - draws about 5 amps (40 amp fuse - right front door control module). Same question.

After removing these 3 fuses I am left with a pretty steady 5 amp draw.

Last few questions:

There seem to be a lot of random things drawing power, unless they are normal or somehow related to this amp being underwater? Will this car continue to cause shorts and problems due to this component being underwater? Or will it be fine after I replace the issues I found.

Are the odometer and radio connected to this amp? So if I replace the amp and connect these 2 components they should come back on? Or am I just dreaming?

I would really appreciate it if someone could give me some info, I haven't seen any of these exact issues or questions on any forum. Sorry if I missed something.

 

[EduardNN]

All electronics located in the cabin and trunk of German cars after 1998, including Mercedes, are terribly protected from moisture, or rather not protected at all, with rare exceptions!
Is it just the odometer (dashes instead of mileage) that doesn't work, or the entire instrument cluster (backlight, arrows)? The instrument cluster should work regardless of the multimedia status.
Open all the units that are most likely to be damaged by water ingress and clean the hydroxides if the damage is not serious, or replace the rotten ECUs. Check the wiring connectors under the carpets on the floor of the car, if there was water there, they are most likely damaged.

 

[bigchevy66]

The instrument cluster going black was very common on these cars, and we always installed a replacement one after verifying the proper power and ground were present to them.

The amp being water damaged will cause all kinds of battery draws and problems with your radio. That's a fiber optic loop system, so a break in the loop (like a dead amp) will cause the system not to work. If the amp is water damaged, then it most likely needs to be replaced.

Regarding checking for battery draws: Mercedes vehicles of this era take roughly 30-45 minutes for everything to go to sleep. Trying to test for a draw before that time is pointless, and will lead you down a rabbit hole. Have all of the doors and hood shut, trunk lid open, but close the latch on the trunk lid, lock the vehicle, and then check the battery draw after 30 minutes. MB spec for battery draw is less than 60mA. Make sure these things have been done and then report back with what the amperage draw is. I would also say to make sure the amp is unplugged when you do this test, since it sounds like it is faulty.

I have used an inductive amp clamp for over 15 years, and it's so much easier and faster than hooking up a meter between the battery and battery cable. I also use it instead of pulling fuses for the same reason. If you don't have an inductive amp clamp, then use your meter like normal.