jerky transmission on 2002 BMW 330i

After driving for a while it will jerk going from 3rd into 2nd gear I replaced the transmission with a rebuild on and it is doing the same thing BMW claims it is not the transmission control unit what else could it be???? i am getting frustrated, other than that the car runs great , can someone think of anything else it could be, or had the same problem? Thanks CG

Asked by for the 2002 BMW 330i
1 answer
as a BMW specialty shop, the first thing that I would do is
drive the car with my scanner looking at live data from the
transmission. if the "new" (rebuilt) trans has the same
problem as the original trans, this is not a trans problem.
the communication "hub" for this car is the instrument cluster; everything from climate control to cruise control gets its signal via the cluster. without driving the car
while you're watching live data is just guessing on what's
wrong. you really need a BMW "master", likely at the best independent shop in town.