jfmiii

So about 6 months ago, I was about 8 hrs away up in northern Wisconsin on a fishing trip. I was about 45 minutes from our cabin and noticed the gear selector on the dash change after overtaking a car on a 2 lane road. It only showed P, R, N, D and did not highlight whether I was in D or R or whatever. I stopped the car, turned it off and back on to no avail. I pulled away and could tell the car was in a higher gear than 2 or 3. It then threw a CEL. I pulled into a parking lot and let the car sit for 15 minutes. I restarted and the car still wouldnt show me whether Im in P, R, N, or D. The car is also stuck in 1st gear. Drove about 10 minutes at 15 mph and shut the car off again. The car was now showing me the gear selector but still had the check engine light. The car was no longer in limp mode, so I drove to the cabin carefully. I let the car sit for an hour and restarted it. Still CEL but no longer in limp mode. I took the car and drove for about 10 minutes and everything was fine outside of the CEL. I pulled over, turned the car off and restarted. Everything was fine and now the CEL was off. Drove the car again the next morning and all was fine--no limp mode and no CEL.

I drove home and the car was fine for an hour and then while on the highway, I look down and I'm in limp mode.....stuck in 4th (ish?) gear so I drove back home around 60mph (2k rpm) the whole way. Once back in Chicago, I turned the car off and upon restart, I'm in 1st gear limp mode. After a few cycles of the key, it was no longer in limp mode but CEL still on. After a few more cycles of the key, there was no CEL and it isnt in limp mode.

I took the car to my indy who Ive used for years. He used to run a BMW dealers service and can fix anything. He had the car for a week and couldnt get the issue to replicate. He spoke with friends of his at Mercedes dealers and they didnt really have any insight. So, after a week, I picked the car up and the car has had zero issues since....

This morning on my way to work, the same thing happened. I also noticed (and this may have happened last time but I didnt notice it) that after turning the car off and restarting, the chime in the cabin upon start up did not play which leads me to think it is an electronics issue. Im sure if I let the car sit for 2 days, the issue will disappear again for several months only to resurface.

Anyone have this problem before?

Carsy

Interested to know how many miles the car has done & whether tranny service has been carried out.

Also how old is the battery?.

jfmiii

tranny service has been done, car has 68k miles. it is an 08 and the battery is original. i was thinking battery was a possibility but the problem went away for 5 months only to come back. if the battery was bad, i wouldve thought the issue would keep reappearing.

Carsy

There are a lot of transmission electrical problems recorded on this site. Try the search box at top RHS page . A lot have changed the conductor plate. JC

centfl-c300spt

Have a shop scan the car. If its a reocurring problem, the ECU will keep the code and the shop can go from there.

IGB

I guess all the times you turned it off and restarted it again, and sinCe the issue was no longer present, the DTC codes were erased after a certain number of restarts. And I am also surprised your Indy did not try to retrieve any CEL / OBD-II codes... Because once the CEL went off, it would have stored the previously existing fault codes as "Historic Codes".

So if it happens again, make retrieving the DTC codes a priority.

That said, I was able to find 3 Technical Service Bulletins related to a "Limp Mode" state. Keep in mind that this is in no way shape or form a diagnosis of your car's issue... Simply what I was able to find based on part of what you described. As you can see below, the critical element(s) in diagnosing the issue and/or determining which of these particular issues was the culprit, is going to be which fault code(s) were triggered at that time.

TSB #1



-----------------------------------------------------------
TSB #2



------------------------------------------------------------
TSB #3



Hope this helps in some way.... Good luck!

jfmiii

thanks for those service bulletins. my indy is sent cars by the local bmw and mercedes dealer to fix and i trust him completely. he is as honest as they come and ive used him for for 15 years. that being said, the car only threw a U0101 fault code which is a communication failure to the TCM. i told him id read that the conductor plate seems to be a common issue after reading these forums and he is hesitant to replace the valve body bc it is expensive and might not be the problem. he has had the car all week and unable to replicate the problem. i found a shop in CA that will repair the TCM:

http://www.shop.modulerepairpro.com/...C35-08-TCM.htm

It is only $270 but I dont want to have him take it apart and send it out there if this wont fix it esp since it doesnt reference the U0101 code as being one of the conditions of needing to repair the TCM.

uhh!!! this is so frustrating!

jfmiii

i think this can be narrowed down to just the conductor plate needing repair or the entire valve body needing to be replaced. does anyone know how can i tell which is needed?

jfmiii

anyone?

Jimbob77777

I have a 08 C63 with the same issue. On Start up it does not have the p r etc displayed. This occurs sporadically and for long periods is fine. I generally turn off and on to fix although some times it does take a while. Was there anyone who knows about this issue and how to solve as I have had to deal with the issue for maybe a year.