2000 ML320 Transmission and Shifter Questions
I have a couple of questions about some intermittent transmission problems I've been having with my 2000 ML320. I hope I give enough info.
1. When I turn the key to the On position, the P indicator will sometimes fail to light up, and instead show only a solid square (i.e., no letter at all, regardless of what range I put it in). If you turn the car back to off, take out the key, and try again, it will usually show a P normally. If that fails, then I will start the car completely, and let it run for a minute or so, then turn it off, and try again -- the P indicator will then usually show normally.
2. Sometimes, even when it shows a P as normal when starting, then I put it in R or D, the indicator will sometimes stay on P.
3. When the indicator does either of these two things (fails to show any letter at all, or it fails to show the correct gear), if you shift it into gear and try to drive, it will go into gear, but stay in first gear and fail to upshift. It also goes into gear very noisily, and with a clunk and a jerk. The car will only return to normal shifting by restarting.
4. Even if none of these problems occur, and the car drives normally, and after driving around for a while I come to a stop, it will occasionally stay stuck in a high gear, and fail to downshift back into first gear. Whenever this happens, indicator will stay stuck on D no matter what you do with the shifter (use the tiptronic to go to 4, or put it in N). The car will actually shift into N (but not to a lower gear).
From what I've read here, this is usually a problem with the connector plate, the 13 pin connector, or a battery that's too low to initialize one of the computers (but enough to start the car), or a sensor in the shifter assembly.
My mechanic tells me that the repair codes are showing a problem with the entire valve body, not just the connector plate. He says that he used to own an ML430 (same transmission), and he had to replace the whole valve body. The part price he quoted me is around $650 (which is much higher than just the plain connection plate, which is only $120).
Here's my question -- Is it a good idea to attempt to fix the problem by moving conservatively -- replace the plain connection plate and the 13-pin connector, clean the valve body, change the tranny fluid, and see if that works? I can do that myself.
Second question: He also says that the shifter assembly must be replaced. There are error codes for that, too. I suspect my wife may have damaged it by spilling water in there, although it's been more than a month since that happened.
My mechanic tells me that a replacement shifter unit can ONLY be bought from the dealer, since there is some security procedure that's needed to code the part to my specific vehicle. To even order one from the dealer, you have to give them your driver's license and registration info and VIN, so the dealer can verify it before setting up the replacement assembly to sell you. Buying a replacement shifter unit that way will cost $700.
None of the parts suppliers for used shifter assemblies tell me that this procedure needs to be done. They sell used ones taken from wrecked cars for $200-400, depending on condition and source.
I do not know who to trust -- the parts sellers who want to sell me a part they claim is fully interchangeable with my car (no programming required), or a mechanic who assures me that he needs to do this and isn't making a profit by ordering a (much) more expensive part.
Thank you all for helping in any way.
Last edited by Magnus3257; 05-19-2013 at 05:18 PM.