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Does anyone know what this might be... I was overtaking down a fairly steep hill, 3rd to 4th gear change at redline, full acceleration then it is free revving with the accelerator pedal. Side to side gear change didn't work, still no gears, stayed in D instead of showing the gear number as it should. Putting it in neutral and then back to drive didn't work.
I had to stop, put it into park, turn the engine off, then on and everything is back to normal. No warning messages etc. Did a transmission fluid drain and fill a few thousand km ago, no problems after that.
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
That can be a brain fart with the 722.6 transmission & a TCU reboot recovers it (usually due to silly driving & yes I've done it too so I'm not blaming anyone. Many things can cause no drive such as selecting reverse while car is rolling forward. TCU detecting an overspeed etc. etc.). But as suggested above first thing to check is fluid level. Also check the electrohydraulic bush on the front RHS of the transmission for fluid leaks. Lift the passenger side kickplate carpet, Loosen the kickplate and check that fluid has not wicked up the TCU harness from the electrohydraulic bush. Common issue with a 10 buck part. Good luck!
Pictures are for W203 but W209 is the same.
Last edited by Glyn M Ruck; 12-29-2015 at 03:53 AM.
Thanks heaps I will look into that. I did replace the bush with the last change of fluid. I suspect it was overspeed. I think going WOT down a steep hill reached redline but was accelerating too quickly to complete the shift in time.
Ok it did it again. No silly driving, or at least not near the time it happened, just brisk acceleration (not WOT) to 50km/hr. I put it back to neutral while slowing down and back into drive which worked. I checked the fluid level, 30 degrees C was half way up the "cold" marking in park with engine running, 74 degrees C was half way up the "hot" marking. Pulled the carpet back and TCU appears perfect. Nothing on the wires except the usual small amount of sticky crap all car wiring seems to possess from the black tape they use. Hopefully another fart otherwise not sure what to do except have MB charge me $$$ for a diagnostic.
not sure what to do except have MB charge me $$$ for a diagnostic.
Just buy Star C4 diagnostic tool. Pays off after 4 visits to the dealer (~$130 US each here). $350 for complete kit and wires + $70 for DELL D630 laptop. Own your own MB diagnostic tool and stop being ripped off by the dealer.
Ok it did it again. No silly driving, or at least not near the time it happened, just brisk acceleration (not WOT) to 50km/hr. I put it back to neutral while slowing down and back into drive which worked. I checked the fluid level, 30 degrees C was half way up the "cold" marking in park with engine running, 74 degrees C was half way up the "hot" marking. Pulled the carpet back and TCU appears perfect. Nothing on the wires except the usual small amount of sticky crap all car wiring seems to possess from the black tape they use. Hopefully another fart otherwise not sure what to do except have MB charge me $$$ for a diagnostic.
Since the TCU is dry from any fluid and you did replace the electrohydraulic bush, you may be looking at a bad conductor plate. That's what happened with my 2003 CLK 320. It started popping out of gear every now and then until it later started happening weekly then daily until the car was stuck in P and would not shift at all.
I got the conductor plate replaced and that solved it. My current 2005 CLK 320 never bothered me with that, but I believe 2003-4 722.6 transmission had this problem with the conductor plate.
It's fairly known problem here on the forum. You can find lots of info on it. If you are a DIY-person, I can share with you a summary of what needs to be done following my research.
Just buy Star C4 diagnostic tool. Pays off after 4 visits to the dealer (~$130 US each here). $350 for complete kit and wires + $70 for DELL D630 laptop. Own your own MB diagnostic tool and stop being ripped off by the dealer.
Thanks, I probably should at some point. Luckily there is a shop down the road with one who charged me $40 last time to read codes. I will definitely look into it in the future.
Originally Posted by xsever
Since the TCU is dry from any fluid and you did replace the electrohydraulic bush, you may be looking at a bad conductor plate. That's what happened with my 2003 CLK 320. It started popping out of gear every now and then until it later started happening weekly then daily until the car was stuck in P and would not shift at all.
I got the conductor plate replaced and that solved it. My current 2005 CLK 320 never bothered me with that, but I believe 2003-4 722.6 transmission had this problem with the conductor plate.
It's fairly known problem here on the forum. You can find lots of info on it. If you are a DIY-person, I can share with you a summary of what needs to be done following my research.
Thanks for the advice, I am aware of the conductor plate issue, it just didn't seem to be a regular symptom that people reported. I will see if any codes come up to suggest it. I found some good writeups on benzworld and here. Haven't had a chance to look through them. My only concern is that I believe it needs to be coded to the car? Or maybe that is just the 722.9?
Replacing the conductor plate on the 722.6 needs no coding -it's just a bunch of electrical contacts. The 722.9 needs coding because it actually contains the TCU.
I will order a conductor plate from pelican parts. Is there anything else I specifically need or should replace while in there? I believe there are some springs but only in the earlier (pre 2000) 722.6 transmissions. It looks like the plate comes with a new speed sensor and the solenoids that are transferred over from the old plate to the new one shouldn't need replacing (they also happen to be 4x $76 and 2x $340 for the 6 of them).
I will get 4L of fluid from the dealer, a new red snap pin, pan seal, bolt/washer, maybe a new fill tube plug and I guess a new filter despite only being done recently.
I will get 4L of fluid from the dealer, a new red snap pin, pan seal, bolt/washer, maybe a new fill tube plug and I guess a new filter despite only being done recently.
Buy 6 or 7L to be on the safe side. When I did mine, as much as 4.5-5L came out since you will remove the valve body as well and there will be a lot of dripping taking place.
It would be nice but unfortunately they are too expensive. Ordered parts. I figured a spare CPS and voltage regulator might be worth getting at the same time and my fuel cap "cord" broke so a new one of those and some air/pollen/oil/fuel filters.
Just buy Star C4 diagnostic tool. Pays off after 4 visits to the dealer (~$130 US each here). $350 for complete kit and wires + $70 for DELL D630 laptop. Own your own MB diagnostic tool and stop being ripped off by the dealer.
I am definitely thinking about this. Unfortunately I don't pretend to understand all of these these systems. The C4 (or compact 4?) would allow codes to be read and cleared for any system in the car? Would it allow things like turning off o2 codes for example with headers or lowering an E55? I presume engine swaps or new conductor plate in a 722.9 would require SDS with SNC coding which is a higher level product again?
I'm not going to lie here, but as to my knowledge, this is the most advanced and powerful scan/diagnostic tool ever invented for MB on the market today and used by MB dealers (as well as SMART and other daimler companies). Technically speaking, this is solely for dealers use only, and chinese replicas.. are for general public who can not afford OEM tool. OEM tool will cost you thousands of $$$ for tool alone and wires plus subscription fees will run you extra.
The C4 name I'm not sure why... maybe command, maybe compact. Who knows..
C4 = Compact 4, which is the wifi version. Personally, I prefer the C3 which requires an RS232 serial port connection. The wifi on the C4 can be flaky, especially in the Chinese clones. A quality C3 unit is better. There are "grades" of C3's. AS with may things from China, there is not a "best one place to buy" since quality varies from unit to unit.
C4 = Compact 4, which is the wifi version. Personally, I prefer the C3 which requires an RS232 serial port connection. The wifi on the C4 can be flaky, especially in the Chinese clones. A quality C3 unit is better. There are "grades" of C3's. AS with may things from China, there is not a "best one place to buy" since quality varies from unit to unit.
Agree, but there are trusted and verified sources to buy with positive feedbacks from members of forum. This is how I bought mine C4.
Just finished the conductor plate yesterday. All the info from the videos above and the benzworld writeup made this fairly straight forward. No idea if the problem is fixed as I will probably need a few weeks of no issues to be convinced. The car drives perfectly so I can't have ruined anything.
For anyone else doing this I recommend 6 liters of fluid. I used 3.5 for my last fluid change so figured that 4.2L (1.2L left over from last time, 3x 1L new) would be enough to account for the extra above the valve body. No! emergency trip to the dealer on Saturday morning for 2L more. There is an enormous amount of fluid above the valve body and conductor plate. I used approx 5.5L in total.
I used the transmission pan as a drip tray- perfect shape for it. I also changed the conductor plate with the valve body in the pan, also perfect to keep clean and for measuring fluid lost afterwards.
This is a messy job no matter how much of a perfectionist you are!
New plate
Thanks pelican parts
I like mercedes new bags, it looks like I just came back from the mall
I used a rubbish bag with a few shop disposable towels (lint free) on top
It never stops
The problem (presumably)
No one really goes over this but when you raise the valve body back into the transmission the only thing you need to line up is the selector mechanism. The blue arrow shows the rod from the valve body which just sits in the notch. The red arrow shows the bar which the yellow plastic support goes around.
Closer look
The transmission won't work otherwise and this can be easily overlooked
The electrohydraulic bush I changed 18 months ago was perfect. Not an atom of fluid between the 2 O-rings. I bought a new one anyway. I find them very hard to get in. I can line it up perfectly but it takes more force to seat it than I can easily apply under the car by hand. I have always used a 32mm socket over the end of it and pried it in with a 12" socket extension using the banjo fitting above for leverage.
I only had to use an extra 100mL to top up after estimating my drips all over the floor. The conductor plate itself had a lot of carbon buildup on the VSS you can see in the photo. Also this sensor piece was quite loose and flaps around. Doesn't seem like the best design. The new one was the exact same design but sturdier from 12 years less flopping around in the transmission.
Torques- transmission pan 8Nm, valve body bolts 8Nm, 3x T30 torx screws that hold the solenoids down 8Nm. Transmission pan drain plug 20Nm, 7mm electrohydraulic bush bolt 2.5Nm or as much as you dare past snug.
12-28-2015, 02:58 AM
hopefully your problem will be solved
