drbyao

I have a 2007 SL550 that was rarely driven, with only 17,000 miles. It developed transmission problems a while ago. Sometimes it would not shift down after coming off highway and the engine would stall. For a couple of times it went into neutral after a stop regardless what you try to shift. In all cases turning off and restarting would get it working again. A local dealer was not able to diagnose the problem suggested to replace the transmission for $8,600. That sounds ridiculous to me. A transmission shop said it's most-likely a conductor plate problem but only a dealer can replace it. Now I am stuck. Any suggestions other than getting rid of this car and never buy Mercedes again? Thanks.

Plutoe

Welcome to the Ford family of products. Enjoy your new ride!

MJ50

moved to R230 forum...

Rudeney

That does sound like the typical speed sensor failure that the earlier 722.9 transmissions can experience. If that is the case, then the transmission shop is correct - it needs a new conductor plate. On that transmission the conductor plate also contains the TCU, and it must be SCN coded (i.,.e have the VIn encrypted into it for anti-theft purposes) and generally speaking, only a dealer can do that. The job usually costs around $1500 and is a permanent fix as the revised conductor plate will not have these problems.

Now, the trick is to know that this is in fact the problem, and for that we need the codes pulled from the TCU. I would think a dealer would be able to do that. However, it is possible that your conductor plate is failing in such a way that it is totally disabling the TCU. I had this happen on my CLK550 (same transmission). I my case, it would periodically, say once a month or less., go into limp mode (basically stuck in 3rd gear, without torque converter lock-up). Shutting the engine down would reset it, but eventually the instances of limp mode occurred more frequently (at least weekly) and them another problem surfaced where it would not shift into any gear until the transmission was warm, up to full operating temp. Of course this happened in the winter, so I had to let the car idle and rev the engine for 20 minutes before it would work. This happens because the conductor plat warps with temperature changes and causes the Mylar ribbon circuit board/cable inside to stretch and lose contact. I suspect this may be your case. If the dealer is unable to pull codes, I suspect it is this issue - the TCU is malfunctioning because the conductor plate is warping. I'd find another dealer who can confirm this and fix it for you. There is almost no scenario where you need to replace the transmission unless something inside has ripped apart and just destroyed everything. This is an electronic issue, so it's all in the conductor plate.

Frederick NL

I stand corrected so removed my comment that was aimed a 722.6 tranny.

drbyao

Thanks. My problem does sound similar to what you have, although it has not progressed to the point of requiring warming up. I will send it to a different dealer next week. The service manager did say he needs to pull the code to make sure it's the conductor plate issue. He sounded more knowledgeable than the other dumb dealership. Wish me luck. Will report back.

drbyao

I took the car to a different dealer and this time they understood the problem and replaced the conductor plate. Cost me $1,800. So far runs well after two days. Hope it keeps working. Thanks Rodney.

Rudeney

Glad to here you got it fixed! Dealer service centers can be such idiots sometimes!

Listeriosis

hey I have similar problem where the car doesn't shift at all !!I have to keep re starting to see "P" on the instrument cluster and sometime that's not even good I could shift to drive and still shows "P" and even though it drives it is either in first or second gear
I have changed conductor plate
replaced fluid
replaced ETC module
nothing so far I still experience limp mode
any advice?

pmercury

iTrader: (2)

Idiots ? you use a very kind word for them
I would use "retard", "scammers" and many other words

Rudeney

Have you pulled codes from the TCU and gearshift modules? You'll need an MBZ-specific scanner for that, not a generic OBDII.

Listeriosis

hi I have had the P040 I believe it was which was a selector switch not activated ???.
question: when you introduce new parts such as: the transmission module (the small box located in the corner of the passenger seat)and the transmission conductor plate do you need CODING?

I have run DAS on this car and it's sometimes a capital F on the "ETC" ? what does that tell you?
and also I got a "F" on the "LPC" that's when I do the quick test but every time it's the same thing I don't know how to really use DAS there is a lot of options.