- Author: Troy Hopp
- Subject Matter: Automatic transmission
- Unit: 09A
- Vehicle Application: 2002 Volkswagen Jetta
- Issue: Hard 2-3 upshift
We recently received a 2002 Volkswagen Jetta, with a 09A five-speed automatic, with a complaint that it would not move. I determined that the fluid was burnt and black, indicating an internal failure. The check engine light was on and it had codes 00652 – gear monitoring not a plausible signal intermittent; 01045 – Tiptronic switch (F189) not a plausible signal intermittent; and 18032 – MIL request signal active (check TCM for errors) P1624. I drove the vehicle, and the transmission would slip and whine for about a block and then the vehicle would quit moving.
Obviously, we needed to replace the transmission; this in turn required replacement of the transmission control module per Volkswagen. VW had determined that 10% of the TCMs in certain vehicles with this particular transmission required replacement of the TCM as well, and ours fell into this category. I also determined that the Tiptronic switch in the center console had been shorted out, per code 01045.
After replacement of the transmission, TCM and Tiptronic switch the vehicle had a very hard 2-3 upshift. I assumed that the shift adapts needed to be reset and relearned. After I reset the shift adapts and drove it up and down through the gears (stop and go) for the suggested 50 miles, the hard 2-3 upshift did not get any better. The Volkswagen never set any codes but acted as though the 2-3 upshift was binding, possibly caused by a valve sticking in the valve body.
I contacted Chris, our lead diagnostician (who remained involved and was a large part of diagnosing the problem), and asked him his opinion; he informed me that the quality-control division at Certified Transmission was doing testing on these valve bodies and suggested that I try a new one. After replacing the valve body, I reset the shift adapts again, and as soon as I drove the car it immediately had a hard 2-3 upshift that again never smoothed out while I was driving it.
I decided to reset the shift adapts again and noticed on the scan tool that on the Basic Settings screen the group number was 001 this time. The first two times I reset the adapts, the group number was 000. This ruled out the valve body as the source of the problem. I reset the shift adapts again using the group 001 setting and found that the 2-3 shift felt normal; however, the longer I drove it the harder the 2-3 shift became again.
This meant that the scan tool had a glitch the first two times I reset the shift adapts; it also meant that we might have a bad TCM. To verify that the TCM was the culprit I decided to put the original TCM back into the Jetta, and then the transmission shifted fine. I didn’t want to leave the original TCM in the vehicle because of the updates, so I ordered another TCM and installed it. After I reset the shift adapts properly without any scan-tool glitches, again the Jetta shifted fine but gradually acquired a hard 2-3 upshift. Now I had two new TCMs from Volkswagen that were creating hard 2-3 upshifts. I had no choice but to reinstall the original TCM, and again the transmission shifted fine.
We took the TCM off the customer’s bill and left the original TCM in the vehicle, since there did not seem to be a problem with it, and will wait for further updates from Volkswagen on the TCMs. The customer has picked up the vehicle and was pleased with the repairs.
For those of you wondering about the part numbers, the new TCM part number is 09A 927 750 BD and the original TCM part number is 09A 927 750 T. Please keep this in mind if you happen to run across this situation, and I hope you can save yourself some time and trouble.
Troy Hopp has been with Certified Transmission since early 2010. He has been in the industry for more than 25 years and is an ASE Master Technician. He is a diagnostician and R&R technician at one of Certified’s retail locations.