bmandango

I let me girlfriend borrow my car and she forgot to close the sunroof before a bad rainstorm. The sunroof was only lifted, not wide open. Now there are a whole mess of electrical problems and I need help figuring out where to start. There were no problems prior to this incident.

This is a base model E350 w/ 6speed auto; no 4matic or sport options.

List of problems:
--Display Malfunction shown on dash screen
--BRAKE shown dash screen
--SRS restraint system malfunction shown on dash screen
--Gear selection not showing on dash and sport/comfort mode inoperable
--Cruise control Drive to workshop shown on dash screen
--rear vent shade is inoperable
--radiator fan constantly runs on high when the car is on
--cd changer seems to be stuck loading/unloading.
--Alarm doesn't beep when using the remote door locks

--There was a GPS malfunction, but I fixed that by cleaning the connection in the trunk behind the Nav unit.

The only moisture I could detect after the rainstorm was in the rear floor boards.

I've check all fuses/relays. I took it to a friend's shop who was able to reset all error codes, but they returned immediately. I have the trunk taken apart right now to try and diagnose the problems. Could it all be in one (or more) SAM units? Or, is it more likely that there are multiple system failures that will all need to be replaced? Should I just drive it to the junk yard?

Thank you in advance for the help.

bbirdwell

Welcome to the world of Mercedes trouble shooting.

Sounds like water is in the CANBUS block connectors. I recommend (and this is what I would do and have done before) disassemble interior parts and spray electrical contact cleaner into every connector you can find. Won't hurt to unplug the connectors, spray, then connect/disconnect/connect several times.

Areas to check:
-Under transmission tunnel cover (electrical components under the shifter)
-Upper control panel (over the mirror)
-Door switches (maybe)
-Pull up the door sills, expose the harness, and clean the CANBUS block connectors (look on both sides next to the seats)
-If there was enough water in the car, pull the passenger side floorboard and clean connections there; lots of electronics in there but beware of the hot lead connected directly to the battery; you can cause some serious damage if you short that one.

PM me your email address and I can send you a document to help locate the connectors.

bmandango

Thanks so much for your response. I'll get to work and let you know how it goes!

raverx3m

electrical spaghetti troubleshooting.


might as well post it on craigslist as "mechanic special"


or throw a lot of moisture absorbers and a heater in the cabin.


I troubleshoot electrical all the time and this is a nightmare..
unless the dealer can plug in their scan tool and tell you which exact modules are faulty. which will probably cost you

rapidoxidation

Well, now I know why the car always makes a point of telling me to "CLOSE SUNROOF!" when I leave the sunroof open after turning the car off. He doesn't say a word when a window is left open, but he's pretty darn picky about the sunroof.
Point taken.

cetialpha5

I'm actually somewhat impressed by my X431 Launch EasyDiag. Got it on aliexpress, they're around $50 and it covers 2 car lines, there are cheaper ones, but then you have to pay extra to get manufacturer specific codes. Works pretty well scanning all MB systems and cheaper than a knock off star system.

raverx3m

also note to self. and everyone. this horse is beyond dead beat to hell brought back and beaten again.


DO NOT LET YOUR GF (or any non car person) borrow your car for any reason because 99% of the time you get stuck with the repair bill
and the person who borrow it is: bruh I donno it was like that when you gave it to me.. i buy you lunch etc...