MB Factory Rebuilt Trans & Computer
 

Please help
My Extended Warrenty company recently covered the replacement of my 722.6 Tansmission and Torque convertor. with a MB Factory Rebuilt Unit.

I there a differce in the computers over the model years (1996-1999). And was this replace along with the transmission. What should I look for?

I notice that although it does not slip any more, it does down shift rather hard from 3 to 2 or 2 to 1 if i brake rapidly. Also when cold and heading out down a hill (long driveway) it does not want to shift out of 2 untill the RPM's are high or I foot shift with the gas petal.
Is this normal

Sorry for the many question in one Post '1997 E300 Diesel'

It really sounds like you need the updated ETC unit. Electronic Trans Control.

A hard 1-2 and 3-2 shift is usually cured by that.

Your upshift delay might normal. It's the converter heat up feature. It's tough to tell by your brief description.

It sounds like you have a mismatched ETC and trans now. When MB replaced my 1998 722.6, they installed a new unit, and along with the trans and converter, they had to install a new ETC to make things work properly.

BTW, the things that you use to brake and accelerate are pedals, like on a bike, not petals, like on a flower.

Are you sure the dealer replaced the trans. with a factory rebuilt. The TCM would have to be replaced to match the updated valve body. The harsh 3 -2 down shift was a valve body problem with the first design valve body. The conductor plate was also updated. Holding 2nd gear that long is not normal. I would take the car back to the dealer; ask them if they replace the TCM. A soft ware fix is not going to fix a hard ware problem. I think they just repaired the transmission.



Tell then to read; Dealer Technical Bulletin 02/99 Group 27. “Check the transmission selector lever switch before replacing the valve body or control module for a shift complaint” transmission range recognition switch

OK Get this... When the Trans was replaced with a Rebuilt I had my Snow tires on the rear of the car, which are a slightly larger diameter the the stock tires. I think 225 to 235. Large enough that the wheel speed sensors detect an inacuracy and the cruise control will fail. I immediatly placed the stock tires on the car when I got it back from the shop.

Bottom line, the harsh shifting was noticed with the stock tires. I put the Snows back on the car as a test and it shift pretty good.

Question: Is there an Adaptation-mode or something that the computer will go through to adjust shift point when a new trans is paired with a trans computer ? Am I set up for a different size tire. Is there an easy fix like disconecting the battery to clear the memory?

:eek: What happened to your tranny? With how many miles?

I just read the other day, that these trannies don't go out, they're the best..... Yet I had read a lot of problems with them elsewhere and now see your poblem....

lmk:eek:

Most 97s need a new ecu with the updated valve body. You will know the ecu is not correct with the replacement trans if there is a large delay into drive or reverse. Updated control module will correct some shift complaints, but not all. You might want to bring it back to the shop with the harsh downshift complaint along with hanging in gear issue.

Regarding the snow tire question, the computer does have adaptation and may take a while. If you unplug the battery, you really have to leave it for an extended amount of time to clear memory. There is no "version coding" in the trans ecu regarding to tire size. The only thing the ecu is coded for is based on your VIN number.Hopefully I helped a little and didn't confuse you more.