Be gentle as I am a MB noob. I saw the other post about the ML trannies free revving, but my problem is different. Whilst towing a light trailer today at about 30mph my trans shifted into neutral by itself and the gear indicator on the dash was all solid, no numbers indicating what gear the tranny was in. I tried shifting back into drive and while fumbling with the lever, accidentally threw it into reverse while doing about 10-15mph. I stopped the car, turned it off in order to shift into park(it wouldn't go into park with engine on) and then turned it back on and shifted into drive. The dash indicator was still all solid and while it would go into drive, it wouldn't shift out of first gear. Got it home(only a few blocks away) and tried to put in park but again, wouldn't go into park unless I turned key to off position. Upon restart, I could put it into reverse, back up, then put it into drive but then after that I could not put it back into reverse or park unless I again turned the key to off and shift it back into park. I've built engines for my Subaru but don't know Jack about MB auto trannies. Thought maybe the transmission ECM took a dump on me, but I'm speculating at this point. I'm also worried I damaged the tranny when I accidentally threw it in reverse while moving forward though I must say, nothing sounds out of the ordinary(no grinding or horrible mechanical sounds, etc). I really hate this vehicle, I spend about $2000 on repairs EVERY year and it only has 80K miles on it. I just got done replacing the radiator in it because MB sees fit to put radiators with plastic end tanks in a $50,000 automobile. Can anyone shed some light on my tranny problems? Thanks so much!

John

 

You could try resetting the transmission, this procedure is for the post 2002 transmission but it may be the same or you may be able to find another reset procedure by traawling the web:

Normal 0 This procedure resets the transmission ECU adaptive learning algorithm:

1. Turn the ignition key to the on (not start) position.

2. Press the gas pedal to the floor and hold for five seconds.

3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.

4. Wait at least two minutes for ECU to reset.


Another take on the same thing:

Since the 722.6x transmissions are "Driver Adaptive", I recently learned you can "send your transmission back to school". I had noticed a bit of a harder shift in one of the cars, so I thought I would give this tutorial a go:

1. Turn the "key" to position "2" (with door closed).

2. Press the accelerator completely to the floor, and hold there for 5 Seconds, then let go.

3. Turn the key to "Off", but DON'T REMOVE THE KEY.

4. Wait FOR AT LEAST 2 MINUTES, WITHOUT OPENING THE DOORS. (It lets the Tranny computer completely "reset" itself)

5. Start the car/truck, and use the driving style you would like the computer to remember. Apparently, around "40" shifting cycles are needed to get the "hang of it" for your driving style.

Good Luck!