Originally Posted by chealse-tractor
Hi I'm trying to find the answer to a problem we are having with our ML270 cdi 2003 in UK.
Problem first appeared in Nov/Dec last year 2007. Drove to work fine go to drive home start car get following lamp’s lit on dash: BAS/ESP, ETS, ABS (orange lamps on left) Brake (red lamp) and once car is moving a continual beeping till the car stops.
Put to MB on to diagnostics they say it the ESP/BAS control module, going cost £950 to fix however we knew that one the wires connecting to this has been chaffed by the left front plastic wheel arch liner. Try to see if there is a recall but no. Decide to park car up till can speak with workshop manager in MB on holiday. I should mention it had been exceptionally wet that week with heavy rain. So the car is parked up for a week we decide to try it no joy still lights and bells. Leave for further week and decide we will risk running it lightly over Christmas to save on hire car cost as had been told it drivable but to not horse it or else could go in to limp mode.
Was about 22nd December partner gets car takes a run picks me up from work, Lights and beeping all out car seems to be fixed had been heavy frost that week. Car has run fine since till last week (12th May 08) on the way home in transit from work and car throws same fault. Get home park up leave for 5min fault cleared switch off and hope sorted. Next morning get 1 mile down the road fault back and still current now. The only thing we are aware of we had heavy raid on the 10th May on way back from friend in remote part Scotland and had no choice but to go through surface water that went over bonnet so need less say into that wheel arch odd was wet last time too when set off but had been dry day when was driving and fault came back.
We spent Saturday last weekend re-insulating and cleaning the wires but came to no joy fault still there. Spoke to workshop manager again agreed cut out bad bit should sort and cancel fault. Did that last night (21st may). Still no joy very disheartened.
We are now thinking has water gotten into the control unit and is either throwing the fault or has it blown the circuit board or something & is the cause. We are reluctant to spend £950 to find it not that. We noticed when we cut the wiring that the copper was black and tried to find clean copper to make a better connection. We feel that may be the wiring is at fault. Has anyone else had this exact problem and what was the out come? We are desperate find a fix but a fraction of the cost if at all possible. Partner be heading to MB again tonight to speak with Workshop manager again. Incidentally we also experienced a flicker in the mileage display stopping displaying for maximum of 20 minutes but came back did again with me one morning got o end road indicated right an came back? Could all this be electrical gremlins? All suggestions and though are most welcome ASAP.
Extremely doubtful that any water or moisture has found its' way into the control module. The module is housed in the fuse/relay box and is completely covered.
The chaffed wire, which has now become oxidized, is the culprit. When oxidation forms in a wire, it will travel in both directions, to both end sources. This will lower the conductivity of that wire, resulting in a much lower voltage reading or signal reading, whichever the case might be. The wire must be traced the full length of its' travel (in both directions) and eliminated.
But first, you must trace to where the wire goes to. It could go to any number of parts or electrical units in this system, which are many. If you can tell me where it goes to and the exact color of the wire, I might be able to tell you what its' function is.