After replacing the 2003 trans in my xk8 with one from a 2004 xj8, the car would drive but would not shift gears. Found a local guy that had wc/sdd software and let him have a go at it. His answer was that the Tcm in the new transmission could not be reprogramed. I took the old transmission apart and removed the tcm and installed it in the new transmission. The car now shifts gears but first to second was like getting hit from behind buy a large truck. Second to third was like getting hit by a small truck and so on. After searching on line, I finally found the instructions to retrain the tcm. You start by gently excellerating through all the gears to 5th gear and 50 mph. Then gently brake to a complete stop. Keep your foot on the brake for 15 seconds and repeat this 4 more times. I did as instructed and sure enough, the car is now drivable. Still is a little hard from 1 to 2, but gets better every time I drive it. Hope this helps someone else.

 

In your original transmission, the wear of the internal parts was compensated by the tcm adapting shift points and hydraulic pressures. Putting it into the replacement transmission, which doesn't have parts as worn out as the original, likely is the cause. The tcm will continue to adapt as you drive, however, the adaptations may never fully be correct. The process you followed is supposed to be done after the tcu adaptations are cleared with the dealer tool, and then the transmission is to go through the drive cycle process to set initial pressures. This is very effective in getting things working correctly. The harsh 1-2 shift is particularly stubborn without a drive cycle adaptations reset.

 

Just go back to the guy and ask him to perform an 'adaptation clear' and then drive the prescribed method for the required distance.

I had a customer with a leaking pan gasket that shifted HARD (from low fluid level) when I repaired it and topped it up. I just performed the adaptation clear and the shifting was back to normal.

bob gauff

 

+1 on what Bob said

with new enough IDS/SDD it's even better but any adapt clear will do

 

You guys are great. I will get the tcm cleared and let you know how it turns out. Would that have worked on the tcm in the replacement trans or was the local guy correct? Thanks again,,, steve