Hey guys. I've got a strange transmission thing going on and I'm wondering if anyone has had this happen.

Driving around normally, or easy roll-on sprints are fine and dandy. The issues tend to come in when I stab the gas hard for fun or to pass someone being a retard. During some of these times, one of the following two tend to happen if the engine lashes the trans too violently:

* I've had the trans lock into a gear refusing to shift up or down. The C/S/M button doesn't respond, nor does the shifter +/- side-side. Restarting the car fixes it.

* I've also had the trans completely disengage. Engine free revs like the car is in neutral. Once the car coasts back down to about 10mph, the trans will lock back in and driving is fine.


No check engine codes or malfunctions or anything. Anyone else experience anything like this? Is there any reset to do for the TCU? Is there a trans limp on these things?


Thanks for the help guys.

 

You can try to reset the adaptives by pulling the transmission fuse......I assume the NAG1 in the MB is identical to the Chrysler and has a TCM fuse. The only time I experienced the whole "out of gear" thing is when we over eliminated the torque management feature......obviously thats not your problem.

Also disconnecting the battery will typically clear all adaptives......its worth a try.


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Thanks for the advice. I had the engine out of the car and never disconnected the battery during the whole ordeal so I'm assuming that something could have gotten confused in the TCU when there was no ECU or engine in the car. I'm going to hook my STAR diagnostic tool up to it too just to check to see if the adaptive settings give anything worthwhile.

I'll be trying that shortly.

 

I hope that resetting the adaptions with SDS will help but it sounds like a torque converter issue.

The more information the better! Good luck.

 

Can you tell me more about the torque converter suggestion? Is there any way to prove it out before I actually yank it? Could that cause my C/S/M button to not work also when these issues happen?

 

I read the trans codes and got the following two:





Afterwards, I reset the adaptive settings and things and things appear to be much better. I'll keep everyone posted on long-term effects.

Thanks everyone!

 

yes i was about to say connect the car to SDS and reset all transmission adaptives.

 

Just a heads up that code 2500 is often not a good sign.

First thing my tech asked me when I thought I was having tranny trouble.

He asked, "Did you get ratio impermissible on your Star? That usually is not a good sign. "

Hopefully adapts reset is the only thing she needs and everything goes back to normal.

 

Your transmission is slipping ... Check simple stuff first like trans fluid ... although the cap has clips that break pretty easily .. almost like a one time use deal ... and you need to find the dipstick tool.

It could be that the clutch packs are going bad causing slipping ... expensive!. As Jakpro1 said ... not a good sign! When the tranny starts slipping like this, the TCU will tell it to go into neutral or stay in gear so you don't burn up the transmission. Also seen it shutdown the supercharger. A reset will put it back to normal but the problem is still there. If you continue to romp on it you'll end up having to replace the transmission.

Weird thing about Mercedes is it doesn't throw ANY check engine lights for stuff like this!

 

If your tranny is on the way out, you may want to consider these folks. They really know how to make 722's bullet proof. They feel their mod are suitable for up to 1000HP

http://www.importperformancetrans.com/

 

Next time you are under your car I would check the electrical connector plug as it's a known issue. Owners have reported strange results if the fluid wicks up the harness and reaches the tcu.

 

I had the tcu get fouled in this exact manner, as have many others. I was experiencing the same symptoms. Changed the tcu and it all went away.
Good luck!

 

Definitely check this one .. I was coming back on to post this exact same thing. One of my buddies said this one is common on trannies (he has dealt with a number of Mercedes transmission issues) especially the fluid going into the connector. Hope I didn't scare you with the clutch pack possibility .. these transmissions are pretty strong unless you are doing neutral drops and/or have high miles.

For the guy that replaced the TCU ... well it could have just been fluid in the connector too. Replacing the TCU would have gotten rid of the fluid too ... not saying it wasn't the TCU ...this is just cheaper to check .

Good Luck!

 

Thanks a ton for the help guys! I did change the trans fluid recently...within the last 1000 miles. I'll definitely check the connector too. I would NEVER do neutral drops and the car has 55,000 miles on it now so I wouldn't think of it as high miles. The old trans fluid was pretty trashed though.

After I reset the adaptive settings on the TCU, the car seems much better. I took it easy for a bit just to make sure the shifts were working fine. Just today I rolled on it to pass a lady at about 35MPH and layed down a 50' set of stripes and all was just fine on the upshifts and downshifts.

Let's hope this was the issue. This never happened to me prior to my engine rebuild so I was a bit startled when it did the first time.

Thanks again! This forum rules.

 

I had the same issue, same codes. Usually the filter gets clogged, then the electrical plate shorts out. Easy enough, trans flush, remove and replace the electrical plate on the valve body and refill fluid to correct level. Should take you about 3 hours. Good luck!

 

My car's milage is up there, and I was told its not worth changing the fluid. I am the second owner and the car was serviced religously by mercedes. Not was the fluid changed. So far no issues with the tranny.

 

socali.luv is correct. with those two codes, the conductor plate on top of the valve body is the cause. If your trans problems come back replace it.

 

Who did your service for you? You may want to take it back and ask them what's going on. If you did it yourself, then you'll have to figure it out. I got some pics below to help for the connector check. This one WAS full of transmission fluid! Also he has seen it wick all the way up to the ECU side (not on E55 but on other Mercedes)

Here are some pics to help you out for the connector portion.
First Pic: You should now what the trans looks like .. you need to look on the passenger's side. The connector is hidden in the shadow in the middle


The white tab rotates to unlock the harness


There is an 8 mm bolt holding the interconnect in


This is the part that you replace. They recommend replacing it at every service but not many people do it. My friend said it is about $65 for this part ... sounds high to me for this thing.. he gets it from the guy he does work for .. he doesn't order it himself so not sure on the price. You could try to use electrical cleaner to clean it up but he said it is just better to replace it.


Some W210s had this issue also and it would ruin the TCU ... you would've thought they would have fixed this issue by now!

EDIT:

If the plug is leaking, you can check if it is covered under warranty:

Courtesy of Konigstiger in another thread:
================START QUOTE===================
MBUSA released service campaigns entitling free repair even out of warranty. Have dealer pull VMI to see if VIN is included.

2004-05 models 163/170/199/203/209/211/215/220/230/463 – Service Campaign 2006020008
2005-07 203/209/211/219/230/463 – SC 2008120008

722.6 transmission, if not included in either SC and still under warranty reference DTB P-B-27.00/47f.

==================END QUOTE===================

The part itself is only $6. Part number is 203-540-02-53

Hope this helps!

 

I just had the trans downshift and lock out of gear again on me today. I had a little sprint from 30-55 or so and when it shifted down on the deceleration, the transition was harsher than normal. Nothing major, but I could sense it wasn't quite the same. Sure enough, it kicked out...engine just free revs with no trans until the car coasts back to 10 MPH or so. I haven't checked codes yet, but I'm sure it's similar.

I'll try to replace this pilot bushing and see if that helps out. I'm going to be upset if this trans is on it's way out at only 55K miles!


Anyway, we'll worry about that if it happens.

 

Refer to aforementioned solution. Your "issue" is NOT uncommon, especially among non-AMG mercedes. It happens all the time to the 211 chassis cars with the 722 transmission. Drop the valve body, remove and replace conductor plate, use transmission service kit with filter/connector, seals, etc. and refill fluid to correct level. Plan on about a 3 hour job, or pay about $1k to get someone to do it right.

 

Thanks for your input. Just a question...can you detail a bit more or give part numbers to the conductor plate mentioned? I found the "pilot bushing" plug thing with o-rings here. I'm just confused as to what I need to look for on the conductor place since your how-to doesn't show images of the valve body removal, etc.

Thanks again!

 

Also check TCU side of the connector. I took mine out today and it was wet too! The TCU side is under the passenger side carpet. There is a steel plate under the carpet that needs to be removed. I am going to replace my adapter!

 

All of this happened to me a couple of months ago. EXACT symptoms and I'm sorry to say but, it sounds like your tranny is going. I tired reseting as you did and all it did was prolong the situation and eventually made it worse. Long story short, out of warranty = $5k down el draino

 

Can you snap a picture of the carpet you pulled out and the steel plate that needed to be removed? I want to make sure I'm headed in the right direction without pulling too much apart.

Thanks!

 

That's what I'm fearing, but I want to try everything possible prior to worrying about that.

Can you tell me what you did for a trans? New, rebuilt/upgraded, used?