2003 Jetta Tdi - Auto Trans issue or computer issue? Help!

Hi, I have a 2003 Jetta Wagon Tdi. It has an auto trans (unfortunately), which I had rebuilt last year for $3072. A little over a year later (and around 19,000 miles later), I'm having some problems. The brake light comes on with hard acceleration and there is a lot of bucking on even mild acceleration on the lower gears when starting. The computer code reads "torque converter", which I had replaced last year. Do you think that this is a computer issue (the mechanic says that this is likely the case, as in many older VWs apparently) or more transmission issues? "Torque converter" was the code last year on the computer read too. Sucks that last year that meant "auto trans rebuild" and this year it means that the car needs a new computer. Technically, it's still under warranty for the trans rebuild. Any thoughts? I am way out of my league here. Thanks!

Oh, also, the mechanic wiped the codes and the car drove just fine for a few hours. So... maybe that indicates computer? I don't know... Help...

Search for threads about 01M transmissions authored by use "CoolAirVW" as it may shed some light on what is happening.

We really don't have much to go on to help you without more information. And the red 'brake' warning lamp has nothing at all to do with the transmission controller.

You say the converter was replaced, but was it a rebuild one or an actual genuine new one from Volkswagen?

First, find someone with the correct software to read your codes. VAG-COM or VCDS. Any guru or trusted TDI mech on this site should have one. Generic OBDII code readers are not good on these systems. They give too little, vague, incomplete, or just wrong info many times. Also, these transmission are not run-of-the-mill. unless the shop that rebuilt them specializes in these or has lots of experience, they aren't likely to be successful in the long-term.

Sounds like you have some reading to do around here. Start by searching "01M" and posts by CoolairVW. this should cover 90% of the issues with your 01M.

Assuming you rebuilt the original, there could very well be issues with the TCM (transmission control module) or with the valve body. Most hard-part failures I have read about seem to be linked to a failure in the valve-body. Many folks, myself included, have avoided rebuilds by getting the VBs rebuilt before hard parts start to fail. There are several warning signs (torque converter codes, delayed shifting, flared shifting). Find out if they rebuilt it (if so, who did it and which parts were replaced) or got a new one. Also, the ribbon connector inside the transmission is very flaky and brittle and may have been damaged during the rebuild. Since it controls the solenoids, it sound to me like if it is failing, it could cause your symptoms.

You should also check the connector on top of the transmission where the control wiring attaches. It tends to collect water and corrode the connections. Try unplugging it and cleaning it with contact cleaner. while the symptoms you describe could be related to the transmission, it sounds to me like it could also be the crank speed sensor. $50 part and easy to replace. when mine was being flaky, I would get occasional hard shifts/bucking, especially when accelerating. It would also crank but not start on the first try every once in a while. While I'm not an expert on transmissions, I did go though a lot of this when my '03 Jetta 01M was having issues.