Just had B service completed on my 70,000m CLK230 Kompressor. Dealership said everything was fine but the ECU was full of oil! A seal has perished on the cam magnet and oil has travelled down the cables into the ECU.
He said it's a case of when, not if the ECU will fail. Looking at $2500 / £1300 for an exhange ECU, new wiring looms and labour.
Is this plausible? The car is not exhibiting any symptoms of low performance, misfiring etc. If the ECU is flooded with oil why is it still working? Will it fail suddenly?
Not an expert here but I don't believe oil is a very efficient conductor of electricity so that is why maybe why it has not shorted out yet. I would think it would be a good idea to not drive the car for a few days and pull out the ECU and clean it off and let the oil on it "dry." Maybe use an electrical parts cleaner spray on it to clean it off as best as you can. I can't believe Mercedes would make an ECU that could be susceptible to getting filled with oil! I would keep driving the car and you get most if not all of the oil out and see what happens. Worst case, you know what its gonna cost to fix. But if it never fails, then you saved a nice chunk of change...
Vehicle: 1988 300 TE. 2001 ML 55AMG. 2003 ML350 (now the new service vehicle...)
Location: Oakland, Ca
Posts: 288
Quote:
Originally Posted by dz111
HMMM, just trying to think how the hell engine oil could have actually saturated your computer!!
It does happen: For instance, on the 140/220 chassis, the transmission electrical connector at the transmission has a seal that fails, and transmission fluid migrates along the wires (being pulled by the electrical current) until is reaches the transmission control module.
Was hard to believe at first, until I ran into a harsh shifting/erratic idle concern on a 1998 S420, and a harsh shift on a 2002 S500.
This applies to the engine oil also. It may not cause problems now, but I would recommend removing the control unit, opening it up (it will not hurt it) and cleaning it out with brake cleaner "parts wash" (it dries fast).
I have a 2002 w203 c-class ..can anyone help me figure out where the TCM (Transmission Control Module) is ..i have had some problems with the engine light which was diagnosed 1st as lambda sensor and then the airmass sensor ...still not right so bought a code reader ..it tells me its the TCM Electronic Transmission Control Module ETC or TCM)
Any ideas where its located so I can check for oil damage and clean ?
ETC is under passenger side footwell. You turn and a remove a few fasteners (one is behind a small plastic tab, another part of the vent on the tunnel. Pull back footwell carpet, not to the seat, just the upwwardly angled part closest to the firewall (this is not MB procedure - they say you'll "damage" the foam padding. Once you discover it is completely soaked with trans fluid that came out of the connector at the trans and walked up the wire, you won't worry so much about it). TCU id the box closest to the pass door. You'll see a metal plate. Three plastic "nuts" hold it on, then it will come off. TCU is the box closest to the pass door. Expect lots of fluid. Disconnect neg. battery cable, unplug two tcu connectors. Spray over and over with rubbing alcohol (again - not exactly a WIS procedure, but it will get you there at much less money than the 25 cans of elec. contact cleaner you would need otherwise). Not a bad idea to pull the padding too. Should be replaced, but I just sprayed the crap out of mine. Finish with contact cleaner. If your model doesn't have the TCU mounted with the connectors facing the floorboard, drill a couple of holes and spin it around. Some genius at MB thought this would help stop the fluid from climbing inot the box. What it does is give the fluid a place to collect. If the plugs point down, gravity will pull the fluid back out when unpowered (the current is what draws it up). Of course replacing the o-rings on the trans harness will usually stop the whole thing.
I had three different shops tell me I definitely needed a new TCU, and probably a new shift assembly. Multimeter tests at the TCU showed it was getting a good signal, and $5 buys a lot of rubbing alcohol (make sure you use 98%). Worked fine ever since. Probably just lucky - but I'll take that anyday.
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