Clk270cdi auto gearbox wont change gear

[alf1956]

Hello fellow members I have been having problems with the auto gearbox on my 55 late Clk270cdi it will go into reverse & drive & will drive but it will not change gear either up or down so I have had my car on a diagnostic machine & was told it is fault code P2206 which is probably the plate in the bottom of the gearbox & I was quoted £600 to do this so I am thinking of taking the gamble on a 2nd box at £250+fitting which I have been told is approx. 2 hours labour. My gearbox is the 5 speed 722.6 & I have been looking around & see that the 722.6 box was fitted to quite a few different models & will they all fit my car with them being a 722.6 box?​

 

[AMGeed]

Don't risk a 2nd hand gearbox Alf. I've been down that road with my E280 and it didn't end well.
First, you have no idea on the condition of the replacement. The guarantee given by breakers is worthless and you won't get one from a private seller. You'll need to change the ATF and filter on whatever you buy anyway to be on the safe side. That is £160 -£200 to add to the bill as well.
It could well be on its last legs and need new parts too . The seller won't know or care.
Secondly, you need the exact model as you currently have. A 722.6 has many variations.

Lastly, I have no idea on your location, but a new electroplate, ATF ,gaskets, and labour should be no more than £450ish at a good indy. I'd take that route every time, even if it needs trailering to an indy.

 

[alexanderfoti]

+1 as above. If you are doing all the labour yourself, a second hand box may be the way to go. It would be far cheaper to get good diagnostics done, rather than throwing bits at it.

Could be the TCU, could be the Electroplate, could be a broken gearbox, If its the electroplate, then £600 is very high, We charge £300 incl 7 L of oil and TC flush.

If you get another box, the 3 digits need to match 722.6XX

 

[th3h1ghlander]

Doing a swap out of the entire box is a gamble without knowing where the issue lies.

As above, get a proper diagnostic on it done and tackle the common issues with this gearbox first. I have a C270, which I believe has the same/similar 5-speed auto, and have had 3 of the issues that many people get. In short, get a proper diag done, codes cleared and a gearbox service (replace trans fluid and filter) and see if the issue is still there. Here are common issues I have seen and read about:

1st issue, easy to check, is the Transmission Connector Adapter Plug. The seals on this and the gearbox go, transmission fluid can seep into the connector and can travel up the cable to the transmission TCU/ECU. Even just in the connector could cause errors and fault codes. If the connector is full of fluid, you can get it changed. If the leak has been bad the level in the gearbox may be off and could also cause issues.

2nd issue (which could be tackled at the same time if you find issue 1) this gearbox is very fussy about transmission fluid level, if it is too high or low it can cause the transfer/conductor/electro plate and solenoids to do funny things like not change gear or put the gearbox into a limp home mode (so can particles in the transmission fluid, causing issues with the solenoids). If it is in limp home mode you will not be able to change the gearbox between winter and summer setting, it will be stuck in one. If you have never had the fluid changed, it may be worth while getting a service done, replacing the fluid and the self-contained filter. Please note that as the fluid level changes depending on temperature, a special dipstick is used to judge the right level at the right temperature.

3rd issue: Low battery power detected by the gearbox TCU/ECU on several occasions may put the gearbox into a temporary limp home mode. If this happens enough times (I don’t know how many) the gearbox goes into permanent limp home mode and will stay that way until the codes are cleared. If you have a relatively new battery this is unlikely but again, good diagnostic would show that code.

4th issue: cracked transfer/conductor/electro-plate or bad speed sensor can also cause issues which is what you were suggesting may be the issue from your previous diagnostic? Replacements can be sourced and videos are available on YouTube which show the process. Again, best to make sure with a good diagnostic. Get the codes cleared afterwards and see if they come back with a better definition afterwards.

5th issue: (there was another but I cannot remember it! I had it in my head a minute ago but it has gone :/ )


Sent from my iPhone using Tapatalk

 

[alf1956]

Hello fellow members, I took my Clk 270 cdi to Europa cars an Indie garage in Sheffield where I am from as my Grandson works there & he put it on the Star diagnostic computer & he cleared lots of faults but it still showed up a gearbox fault so I drove off on my way home & a soon as I hit the open road the gearbox was changing up & down a smooth as silk & kept like that all day but later in the day after around 20 miles it made a jerking similar to if you let the clutch out too quick in a manual car & it was then a bit intermittent with its gear changing. It has already had a fluid & filter change. Any thoughts on this ?

 

[LostKiwi]

It needs the codes read again to see what's reported. Guessing with these boxes is expensive.
If P2206 recurs then there is a good chance the conductor plate needs changing. Fairly easy DIY job if you're competent with spanners.

 

[umblecumbuz]

During your gearbox troubles, has anyone actually checked the fluid level?
I don't think it would be a primary cause, but it is always a basic check - costing nothing and possibly eliminating one potential hiccup.

This sticky will give you background info with photographs and costs on what's been said above:

https://forums.mercedesclub.org.uk/...cing-conductor-plate-in-722-6-autobox.146696/

 

[John Laidlaw]

It needs the codes read again to see what's reported. Guessing with these boxes is expensive.
If P2206 recurs then there is a good chance the conductor plate needs changing. Fairly easy DIY job if you're competent with spanners.

This entirely ...

 

[alf1956]

It has had a new gearbox filter along with new atf fluid less than 100 miles ago which was done to see if that was the problem, drove it this morning for around 3 miles & it was sweet as a nut changing gear lovely !

 

[malcolm E53 AMG]

Yes as LK and JL in all probability the electric/conductor plate, when mine went it only misbehaved when the gearbox was fully up to temp (restart would reset it) but eventually (as they all do) stuck in second gear permanently