Well, I bought it and right as I drove it away "gearbox fault" appears on the display. It threw the following codes P1111, P1730, P1734. It stalled once on me because of the transmission. It drives fine in what I believe is 4th gear and reverse doesn't always work. Any ideas? The transmission was rebuilt 25k miles ago (a $4000 job), could it really need to be rebuilt again? Any advice is appreciated.

 

Is there any warranty left on the trans rebuild? Have you looked up those fault codes to see what they mean? I would start with the basics and do a fluid change but investigate the old fluid. Look for metal shavings.

 

I'm in the middle of doing the tensioners on it, so the transmission has to wait. It was rebuilt in 2006 so I doubt that the warranty would cover it (if it exists). If the worst comes, I'll buy a rebuilt unit and swap it out. The fault codes indicate "gear control malfunction 1,2,3,5" I can trick it into reverse if it registers a fault. This leads me to believe its more of an electronic issue than mechanical. Plus I do not hear grinding noises, which is a huge bonus. I can get the gears to shift by using the J-shifter and do it manually starting out in 2nd. The gear changes are not the smoothest, but it does work. I'll flush the fluid once the tensioners are done and then take it to a Jag shop anh have the transmission computer looked at to see what she is saying.

 

Sounds like a plan. By chance did you disconnect the battery overnight to maybe reset the computer?

 

There were issues with the transmission wiring harness on the early XJ8s. The movement of the engine and trans would pull on the harness and cause connection problems. I'm sure you can find something on this with a search.