Friday I had the engine compartment fuse box cover off because I wanted to disable the fog lights, I wasn't sure if I wanted to put them back the way they were so I left the cover off the fuse box figuring it wouldn't rain anytime soon. Also before I drove away, brilliantly I decided to hose the pollen and bird crap off my windshield and as I drive down the road the instrument cluster started displaying all types of error messages and the nav screen started popping up and down. I pulled over, turned off the car and then it wouldn't start. Called my dad and he helped my tow it back to the house where we disconnected the battery and dried out the fuse box. After waiting a bit we put everything back together and the car started and seemed to be okay, except the wipers didnt work, one of the fog lights was stuck on and the check engine light was on. After disconnecting the battery and reseting everything the check engine light was gone and the fog light was no longer stuck on. The wipers still didnt work.

Still with the fuse cover off (stupid but i thought i'd let it dry out more with engine heat), I went for a drive to town, the only thing the car did was squirt washer fluid on the windshield every couple minutes and the wipers didnt work. Suddenly the wipers worked and everything was fine, but then the washer fluid went on and stayed on and it drained out the whole tank. The cluster started going crazy again! obviously because I stupidly left the fuse box cover off and the washer fluid got in it! I flew home (10 minute drive) with the cluster freaking out because I knew if I turned it off the car wouldn't start.

I dried everything thing out again, this time took apart the fuse panel plate and dried water out under their and this time when I put the battery on it was the same. After disconnecting the battery a couple times, sometimes its normal and then after 5 minutes of running it goes back to its error messages.

I waited a couple days with the battery disconnected and this morning reconnected it. It was totally normal for the first five minutes of running, but then went into its whole error routine. I figured out this morning that it wasn't only because I left my fuse box cover off, but because the drain holes for the water duct under the windshield was clogged, water was literally draining right into the fuse box.

here are videos of the problems:



Does anyone have any idea what I need to replace to fix this? the front SAM? I noticed a logic board in the fuse box, the whole fuse box assembly? I really hope I don't have to replace each and every component that isn't working (ESP, cruise control, cluster etc. )

the good thing is the car runs perfectly fine so its not the ecu or anything like that.

any help would be appreciated!

 

Had the same problem for more than a year with water getting into the fuse box/relay area of my exotic V12. A specialist in rebuilding wrecked exotics resolved most of the problems in a few hours. A suggestion may be first removing all fuses and inspecting relays for moisture, drying cautiously what you can with a hair dryer.

If you do not wish to go to MB service, who can (if they are competent) through looking at error codes perhaps pinpoint the source of the fault. Most wrecked exotic rebuild specialists have experience in solving these problems as a front end collision usually damages the fusebox area, being located just behind the front fender.

Cost me a well-spent $1k DLS, also this shop removed an aftermarket alarm system which had been terribly installed and was the cause of constant battery discharge. The original manufacturer agency quoted about $13k DLS as they wanted to replace the entire wiring harness.

 

Holy Frijoles.

Have you taken the whole thing out of the car? I would do that. I would take it all out, take as much of it apart as possible. Clean all the connections and make sure it is dry.

You should not have to replace other things like the ESP module or anything.

 

After a lot of time and disconnecting and reconnecting the battery the car eventually got almost completely back to normal. Its been a couple weeks now and every things working great except:

In a single drive the headlights will go from being stuck on all the time to working normally. When they are stuck on all the time the light switch is useless and you can't turn on the fogs or anything. Also when you unlock the car at night the lights do not come on. While driving it literally switches from good to bad, so during the day the headlights will be going on and off.

Also,

the switches under the radio for the heated seats and rear sunshade don't work and lately the ESP off and hazard switch doesn't work. At night all the interior illumination is okay except for the illumination behind these buttons, with the passenger airbag off light the illumination literally flickers on and off, real weird. There was also a point when I could get the heated seats to work by holding the button for like 7 seconds.

This is obviously a result of water getting into the fuse box. Nothing else happened to the car. Do you think I could get the SAM in the fuse box reprogrammed to fix this? Or are there deeper problems then that?

This is the last thing I ever thought would of happened to my prized possession. I hate chasing electoral gremlins and am hoping one SAM reprogramming or replacement will fix this!

 

It does sound SAM related.. I'd think replacement would be the way, not sure reprogramming will help.

 

I may have a front SAM to sell soon. I am in the process of adding Active Blind Spot Assist and I have to put a new SAM in. I don't know if my old one is correct for your car though. Post the part number off your SAM and I will check it against mine.

 

The OP's adventures here sound like a Seinfeld episode... haha.