Hello, Bought this car last year without enough due diligence and now I'm paying the price. The AT shifted buttery smooth until it stopped up-shifting out of 1st. The indicator lights that show when it is in Sport or Normal mode are blank when the shifting stops working. I had bought an expensive battery to move it around while I did the t'shooting and repairs. It's an inexpensive battery which drains after 3 or 4 days if we don't start it or charge it frequently. I was wondering if installing the correct battery would fix the shifting problem? The car really comes alive electronically when I charge the battery for a couple of days and everything seems to work: Navigation, Cruise Control, and all the other electronic goodies which don't usually work. But all the electronics drain the battery (too small) and we lose all that stuff.

I wasn't making the connection between the amount of charge and the AT's functioning until recently.

Any ideas if I might be right?
TIA,
Larry
2006 MB E350 AWD

Low battery voltage can cause the 722.6 to go into limp home mode. You need to find the cause of the battery drain and you'll have to clear the codes in the TCM to get it out of limp home mode.

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Lets break this down:

Given the car was working at time of purchase and did so for a decent amount of time, I doubt any pre purchase inspection would have uncovered anything. It is a 13 year old car after all. Also, actual limp mode on a 722.6 is 2nd gear however you could actually be starting out in 1st. .
The shifter on these cars is an electronic device that communicates with the transmission controller, you _NEED_ a scan tool to look at live data and codes. The shifter might be commanding the trans to shift in manual mode and a scan tool will show requested gear / position of the shifter. I'm also wondering if , in normal operation , when the shifter is placed in manual mode the Sport or Normal lights go out. Try a manual shift mode when everything is working properly or when the problem occurrs.


Battery size isn't a problem if it goes down after 3 - 4 days, a larger battery might only get you another day and won't solve the problem. You could run the car on a lawn tractor sized battery and once the engine was running , not have a problem.

You really need a scan tool and to check voltage of the charging system. Given all of these problems are occurring there is a common failure point. I've seen alternators have a shorted diode cause battery drain , apply electrical noise to the system that causes all sorts of problems.

Above all, diagnose and don't randomly throw parts at the car.


If the alternator is working properly and the engine running, a drained battery will recharge and the car operate properly while it is being charged.

This is a textbook example of a faulty shifter, however...….....make sure you have the correct battery in the car and that the charging system is working before you do anything else.

I will gently hold that if the battery is functioning properly, a lesser amp hour / reserve capacity won't cause the car to have the issue he is having.

Is this shifter like the other SAM modules in that it wakes up when it sees CAN traffic or does it receive key on power to wake up? I can see the shifter staying awake / waking up other modules and draining the battery.

Thanks gang, I will check for shorts as that seems like the problem I need to tackle first. This has been really frustrating as the car shifted buttery smooth, then all of a sudden it stopped upshifting.

I tend to agree than the Shifter is likely at fault. (but I will work through each fault before I start buying parts).

BTW, I have been told it is impossible to use a Used Shifter as they must be programmed to work with each car. This doesn't sound right, but I don't work with electronics much.

Any truth to that? It will increase the cost significantly if it's a New Only, Dealer Only part.

Thanks,
Larry

The shifter is considered a "theft relevant part" and is tied to the car meaning you can't get one from junk yard and swap it with any expectations that it will work.

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Jim

Thanks Jim, That's fascinating! They think w/o this design feature people would walk around carrying a used shifter so they can pop the old one out and put the new one in and just driving away? LOL, ;-) Please don't think I doubt you at all, it just sounds like something bureaucrats would come up with... Probably the same ones who came up with the biodegradable I had to repair on my '91 300.

I'm sure they had good intentions, it just bothers me when I am "protected" so much it makes things harder for me to repair. I suspect it's a Dealer Only part. I wonder if there's any NOS around? (Say, anyone need a nice car for VERY short distances where 2nd gear is all you need?) I'll make you a deal! ;-)

I still need to have the codes pulled but I look at this as a worse case. I still plan to find the short that is draining the battery, maybe it will be something bizarre?

Just talked to the dealer and the price for a new shifter is $753! Labor is probably that much again so the total is likely between $1k and $1.5k. Hmm.. I wonder how much a used tranny would be, if that would fix it. Looks like I have an gorgeous, expensive paperweight!

I think I'd be better off it it were stolen - at least my insurance would help a bit...
Thanks again Jim, I appreciating you explaining it to me!

The reason benz made these parts theft deterrent is because in other countries where chop and ship shops are plenty and these cars cost a literal fortune. A car can land in a shop and disappear within 2 hours at max.

They sell spares and other pieces - So benz came up with coding the parts which makes it harder to sell (this lowers insurance rates for the owner of the car - Look up Ford Sierra Cosworth history in the UK to understand it).

I remember landing on a website that offered a 722.6 shifter rebuild service for the later style PRND +/- type shifter - cost was high but they could do it - they also repaired some old radios I think. - let me try to find it.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Hi all, Sorry for the delay - health issues took precedence. Anyway, put the correct battery in the trunk and the display next to the odometer is now working properly - the gear selected shows to the left of the odo and the Trans mode shows to the right. So we solved that problem. Also, the shift lever no longer gets stuck - it moves from P to D, stops at R and N, then goes to D & back to Park. (Before it would get stuck in D and we had to shut it off to get the shifter back to P & remove the key).

Unfortunately, it is not upshifting properly - it fails to upshift out of 1st or 2nd - which ever one it starts in. Everything else works though. Bottom of the AT is dry and it starts instantly and runs smoothly. Could fresh ATF & filter help this? Not sure when the PO last changed the ATF but I did check the level. I guess it's worth a shot, right? Anyone recall how much ATF I need? It's a 722 AT (06 E350AWD).

Man! I really miss our 91 300D! Rust got it and wouldn't let go. Probably could've kept it forever except for the rust.
Thanks for any thoughts.....
Larry

Your 722.6 transmission is stuck in limp home mode. It's a common problem when oil leaks into the wiring harness or if the conductor plate fails. After you fix it the only way to get it out of limp home mode is to use a scan tool that can read transmission codes.

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The above statement is a very common mis-understanding concerning the 722.6 transmission.

Once the issue that caused “limp mode” is resolved, normal transmission function is restored, whether or not the fault codes are erased.

Let’s use a faulty speed sensor in the conductor plate as an example. If a momentary fault occurs a trouble code is stored and the transmission will default to protection, or “limp” mode. The transmission will have limited function for the remainder of the key cycle, even if the “glitch” is momentary, which they often are. If the key is cycled and the fault code is still “CURRENT” the transmission will remain in protection mode.

If however, the fault is no longer current at the next key cycle, the transmission will resume normal function and the fault code will now be “STORED”.

Mine required clearing before normal function was restored.

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Hey Gang! I finally installed a Alt (180W) and it is producing a solid 13.8v with the engine running. We test drove the car enough to learn the shifting has not been restored. From a standing start, it is either shifting from 1-2 or 2-3. but it shifts no higher. At roughly 40mph it is turning at ~4000rpm. I was considering replacing the conductor plate & then wondered if there is a test for the solenoids or if I should just plan on replacing them all? Or maybe they can be cleaned and restore them? Also, are the Solenoids all the same or is there a different one for each function? Thanks again for everyone's suggestions & comments! btw, The codes my $100 reader finds P0016 & P0017 which both relate to cam components which I am familiar with. But no transmission codes. I plan to take it to my Indy to see if his monster reader will find add'l codes...

Damn it's been 2 years and still not fixed?

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