I have a 2002 Xj8 that will shift very hard into second gear and when you let off it has a hard time picking between first and second. When it shifts hard the gearbox fault code comes on then asc light flashes for a breif moment. When the gearbox fault code is on the car goes into a limp mode where it is pretty gutless until about 30mph and shifts just fine. The tps seems to be reading correctly and I can't see what any of the other transmission sensors are with my code reader.

​​​​​​I Think the transmission is bad but I haven't yet taken off the oil pan to see if there is a buildup of metal on the magnet. The atf is really thin and brown color but it doesn't smell burnt.

If any of you guys could help me figure out if it is the trans or the tcm or whatever that would be a lot of help.

gearbox fault codes Stall speed code
Gear 1 incorrect ratioGear 2 incorrect ratioGear 3 incorrect ratio

 

It would help to put the actual fault code numbers in the post. Non Jag readers often do not tell the whole or correct story all the time in their text version.