722.6 transmission in R129 - PeachParts Mercedes-Benz Forum

Deneals · #1 06-22-2006, 11:12 PM

Tonight, while driving from dinner, I notice a problem.

The car will not start in 1st gear, even though the W/S switch is set to S. *The car will not downshift when flooring the accelerator.
I have a feeling that I’m experiencing an electrical glitch.

Perhaps the car is trying to go into limp home mode. *I neglected to shut the car off and restart, so I’m not sure about that part.

Any comments? Anyone have any similar experiences?

mbdoc · #2 06-23-2006, 08:15 AM

No matter what, if you select 1st gear & the "S" switch is on the trans should start in first...IF not get to someone with MB code reader & have the TRANS computer scanned!...Has the fluid been changed & the electrical connector checked for fluiid?? Has any liquid been spilled on the SHIFTER area??

Deneals · #3 06-23-2006, 08:38 AM

Quote:

Originally Posted by M.B.DOC

No matter what, if you select 1st gear & the "S" switch is on the trans should start in first...IF not get to someone with MB code reader & have the TRANS computer scanned!...Has the fluid been changed & the electrical connector checked for fluiid?? Has any liquid been spilled on the SHIFTER area??

_____________________________________

THANK YOU! Fluid was changed at 92k.
Your post helps me to decide whether to use my indie or take it to the dealer.
To me, this is a newer car. To the dealer, its an old POS. I am never sure if a component can be scanned or if it is not computer related.

Last time I had a problem, (with the ACC) my indie couldn't diagnose the problem, and when I took the car to the dealer, I was surprised when they just threw parts at the problem instead of using some computer diagnostics. That was NOT an inexpensive visit.

blackmercedes · #4 06-23-2006, 09:07 AM

If your indie has SDS and good MB knowledge, then go there. My own has done so much 722.6 repair/replacement work he can diagnose trans problems in about 10 seconds. If you do need a new trans, the cost of the 722.6 has come down dramatically.

If your indie is having trouble diagnosing problems, think about switching mechanics...

deltajetfixer · #5 06-23-2006, 11:52 AM

Quote:

Originally Posted by blackmercedes

If you do need a new trans, the cost of the 722.6 has come down dramatically.

ReallY?

What are they going for nowadays?

blackmercedes · #6 06-23-2006, 12:54 PM

My indie does a 722.6 in most models (not V-12's) for about $3000 incluing all parts, labour and misc. bits. Four years ago it was $8500.

Carlos Serrano · #7 06-26-2006, 11:44 AM

there was a thread about similar problems with a 722.6 posted by jjrodger on the SL forum and the problem with his was fixed by the local MB dealer by replacing the MAF, something about erratic signals from a defective yet operational sensor causes the electronically control tranny to misbehave,
might as well check it out is a hell of a lot cheaper.

Deneals · #8 06-27-2006, 09:52 PM

I ended up having the car towed to my indie shop. The resolution was replacing the “Transmission Electronic Kit” which is an interface between the transmission operation and electric contact points to the computer; a square plastic unit. To replace this part, the valve body on the transmission had to be removed & replaced.

Got the car back and everything is back together. The car actually seems to shift better than before, especially when shifting manually.

Thanks to all who were interested.