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1999 ML Auto Trans

3K views 25 replies 8 participants last post by  DrX 
#1 · (Edited)
I have a previous thread about this on here but now another situation (different) came up. As odd as this sounds, less than 2 weeks after my ML trans went goofy, our 2004 C240 just stopped driving with no warning at all. I was sitting at a traffic light and began to move when all of a sudden the car stopped moving. I made a quick turn ( I was in the middle of an intersection) and drifted off to the side of the road. Tried reverse and drive , nothing. I called a friend to get us home and arranged with my brother to come and tow me the mile home. After finding out he could not do it for a few hours, I had my daughter drive me up to put a note on the car and (after reading up on this on this forum) I decided to try it again. It started up, put it in gear and drove it home (slowly) After getting home, went back out later and nothing.

Now the reason for this long explanation. I had purchased a new conductor plate kit and put in on my ML, but learned later than I was supposed to engage the shifter lever. Now the car trans did exactly the same thing so after much reading, decided that it was 85% chance ( read that here also) that it was the conductor plate or the plug. Removed the plug and it was covered in oil, so cleaned that up and put in a new one and closed it back up. Nadda. Since my truck only needed to be put back together, I moved to that. Tried to reconnect the new plug, could not for the life of me get the 7mm bolt to screw in-. Thinking that I might have bent one of the pins, I removed the valve body and plate and replaced the plate with the one I had bought for the C240 since I did not use it and the new plug went right in. Put it all back together and guess what. Nadda AGAIN. Not sure if my next step is gasoline and a match, but if someone can somehow figure this out I would GREATLY appreciate it..

PS thanks for taking the time to assimilate the entire post,haha
 
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#7 ·
You need the car scanned. Either get a pro grade scanner or a Star System. If the trans is operating erratically it has codes stored and there may be a CEL. If it has gone into "limp mode" you will need one of the scanners above to clear the code or the trans will remain in "limp mode" which is characterized by harsh engagement going from park to reverse or park to drive and it won't shift out of second. Either way you need to know what's going on inside and you're guessing until it's scanned and then you need to have the ability to clear the code when you correct the problem. Post the codes and we'll see what you have.
 
#8 ·
thanks VVR- The problem is that the nearest dealer is over an hour away and it is pretty much cost prohibitive to have it towed that far to have it scanned. I have used the truck for softball coaching and it has around 276K and has taken quite a beating over the years towing equipment trailer for weeks at a time up and down 95 ( i used to live in Harleysville PA) and parking lot dings and dents. To get it repaired at the dealer would be more than the truck is worth at this point. That is the main reason for doing it my self. I have learned my lesson over the years being on the road and having to rely on Indies. Like the dealer, their solution is add new parts and cross their fingers but ,if it does not work out, just add more new parts till you get it right. That way, they make $$$ on the parts and the labor. Pretty much the same situation with buying a star scanner. That is the reason I am requesting help so I do not have to spend a couple thousand dollars on a car that, value wise, is only worth a couple of thousand dollars. It is to good of a machine to just casually discard it so I really want to keep it and use it for another few years like it was meant to be used. There is a new shop on Amelia Island, so I am going over to talk with him tomorrow. It just seems so crazy that both cars have the same problem within 2 weeks.

No limp mode, no signs of impending trouble, no alerts, vibrations, surges, etc. They just stopped driving.
 
#9 ·
Then I would suggest you get a good scanner capable of reading and clearing codes including ones in the transmission. There are several good scanners that are capable of,doing what you need. Nothing irritates me more than throwing parts at a problem without doing the proper diagnostics. You are just guessing without the diagnostics and most times the guess is incorrect. Check the forum for an affordable scanner and make it your friend because as long as you own these cars you will need it. I too live in an area where the closest dealer is over 1hr away so my best friend is a SnapOn Ultra Pro Scanner. ( yea I know I gotta get a life). ;-)
 
#10 ·
OK- First of all, thanks again for all of your help. Things got a bit sidetracked for a while with some health problems and my daughter being home for the summer from college.
so here is the update.

For the 1999 ML320- 097, 098, 099, 100, 101 and finally 116. These seems to be solenoid related so I am wondering if the solenoid valve malfunctions or could it all be simply control plate related?

The C240- P2500 (trans ratio?) P2503 ( not sure what the code means) P2200B= I may have written this one down wrong- (spec Y3-6N2 not compatible) and P2221- same code Y36B1 Imputable.

Now I know this is asking a lot, but I have put to much time in to these projects (still very odd that both happened within 8 days of the other) to have it taken to a Dealer or trans shop now. I ask again to PLEASE share your knowledge with me.

Again, all my thanks for any assistance you can offer.
 
#11 · (Edited)
ok- after searching for hours, I finally found a code explanation that I could find the ecm fault codes. Now my problem is, they are so technical that I can not figure out what they mean, lol. can anyone help Please?

P2500 The transmission has an impermissible transmission ratio.
P2503 The gear comparison is negative or the target gear is not reached.
P2200 Component Y3/6n2(speed sensor 2) is faulty or the sensor supply has Short circuit.
P2221 The signal of component Y3/6b1 (ATF temperature sensor) and (or) Y3/6s1 (Starter lockout contact) is implausible.

Is there a simple explanation that I can understand, lol?

Since I have replaced the control plate and plug and discovered fluid all of the way up to the ecm plug in ........ I have a funny feeling that basically all of those codes together mean replace or rebuild the TCM?
 
#12 ·
It would be the next step take. Remove it from the truck and open it to see if it is contaminated.

I am also assuming that when you cleared the codes you cleared them from the transmission control modules and then the ECM. If they were not cleared from both places then the truck will stay in limp mode.
 
#14 · (Edited)
After work on the tranny codes must be cleared in all modules. You have done work on it, but never mentioned "clearing" of codes

Despite of the codes pointing to the conductor plate, I would do the following:
1. Clear all the codes & see if the car moves. If not then
2. Open the TCM/ETC & make sure there are no traces of oil in it. Clean it properly & put it back together. Clear the codes & see if the car moves. If not then
3. Make sure the pilot bushing is properly installed & in correct place. Since you have just changed it, I am assuming there is no oil in it. Clear & try to move. If not then your conductor plate is faulty or not compatible.
I hope you bought original MB parts..........
PS. before all this post the part# of the conductor plate to make sure it is compatible with the ML.
 
#15 ·
Re

If you own a ML 320 the item below is your friend :laugh

It can read codes AND erase them !! 220 bucks and free shipping !

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#16 ·
Would suggest this only after verifying that you have purchased the conductor plate for the ML. Understand that the conductor plate is like a primitive circuit board with connectors on it that activate the solenoids based on queues received from the sensors as interpreted by the TCM. If the plate is warped ( Chinese made are known for this because there is no quality control) then connections will be irratic between the solenoids and sensors and since the sensors are formed with the pressing of the plate they can't be fixed and the plate must be replaced. Check the solenoids separately either with a DVOM or momentarily put 12 volts to the connectors and watch/listen for a click. No click means the solenoid isn't working and must be replaced. The fact that the vehicle restarted and was then able to be moved means that the codes weren't set in the TCM or limp mode would have engaged which is characterized by harsh shifting from park to any gear forward or reverse and the inability to shift out of 2nd gear. And again make sure you clear all the codes in both the ECM and TCU or the vehicle will remain in limp mode. Good luck.
 
#17 ·
Sometimes life gets in the way of car repairs, lol , so sorry for the delay in updating. After Noodles agreed that the logical (if there is such a thing in the electronics world, haha) was a faulty ECM ( and since I did observe a lot of fluid at the plug and at the plug at the connector at the ECM ) I have sent the ECM out for rebuild. It should be back in a couple of days and I will let you all know how things have gone.

Again, my sincere thanks for all of you for your help and suggestions
 
#21 ·
This is on the C240. The ML is on hold until I get my wife's car repaired. I did pull the TCM and there was oil inside and around the plug and judging on how it is positioned, flowing in to the unit is almost a certainty. The codes all indicated some type electrical fault in the conditions of various solenoids and I have read that they rarely go bad, the signal being sent to the TCM is either corrupted or the message being sent is not functioning properly from the plug in at the TCM. With a new control plate installed, a new Connection plug with new seals and a different dry harness, that is why I thought Noodles said inspect it and see if it was bad. I did try to take the unit apart, but it was very difficult to open it and I did not want to break it and end up with buying a new TCN with the accompanying requirement to have it programed at the dealer.

The codes point to different signals and implausible signals I am not a mechanic, but my experience with other electronic problems is that a bunch of components rarely go bad one after the other.

The 2nd factor in "blaming " the TCM is that when the shifter is moved fro park (and it does move at the connector- I had my wife move the shifter back and forth after I put the valve body back in.

Since the car showed no problems at all and just stopped driving, would the TCM send a message to the ECM and they both would have shown up in the codes?

Again, thanks for you patience in understanding non-technical descriptions and assumptions.
 
#22 ·
I would have attempted to clean the unit before I sent it out. It is a common problem and it rarely results in a bad TCU. The metallic particles within the transmisssion fluid conduct electricity and when it wicks up to the connector it causes erratic operation. A good shot of non residue contact cleaner on both the connector and the unit would take care of the problem under "normal" circumstances
 
#23 ·
Yes, I did do that and even used another harness but judging from the area where the trans fluid was congealed on the top of the TCU it appeared to be a slight "bulge" in the plastic case, so it could have easily seeped in to the unit itself. Is my assumption that if it was something mechanical within the unit itself there would have been some kind of indication of trouble and it would also have sent a code to the TCM to alert it that a problem was present? I will list the codes again so you can see if you think any of them would indicate that?

P2500 The transmission has an impermissible transmission ratio.
P2503 The gear comparison is negative or the target gear is not reached.
P2200 Component Y3/6n2(speed sensor 2) is faulty or the sensor supply has Short circuit.
P2221 The signal of component Y3/6b1 (ATF temperature sensor) and (or) Y3/6s1 (Starter lockout contact) is implausible.

Thanks again,Ray
 
#24 ·
This is for the 2004 C240 and just stopped shifting and driving. When I got it home in limp mode, it would never engage and gears again. Ok- I am now out of options it would seem. I have replaced the conductor plate (2 times once I heard the China ones sometimes warp), the plug with new gaskets, insured the shirfter pressure rod (forgot what it is called) is engaged. had my wife go through the gears and it shirted back and forth with no sign of interference, cleaned and dried (compressed air) both ends of the harness, replaced the rebuilt TCU ( unhooked the batter and charged to full capacity, installed the TCU and then hooked up the battery) and carefully checked the plug adaptor connection to insure it was solid and dry. The mechanic that did the codes and cleared them is a very reputable mechanic so I have no reason to doubt him doing it correctly with his snap-on pro reader

Any further suggestions?
 
#26 ·
This is for the 2004 C240 and just stopped shifting and driving.
The descriptions of your problems are not very detailed. What exactly do you mean by it "just stopped driving"? Was there no response to pressing the accelerator?

You said you tried a different dry harness. Does that mean that you are using the old harness again? It might be damaged if there is a short circuit to RPM sensor 2.

Please have the codes read again. If P2200 is back, you need to repair/replace the harness and clear the codes professionally again.

(Possible cause) RPM sensor 2 (Y3/6n2) --> (Complaint/problem) Transmission is in electrical limp-home-mode --> Harness is damaged from ETC control module to each RPM sensor. (OR) RPM sensors are faulty.
 
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