After my first post "ZF6HP28 Transmission Woes", I tried to no avail to fix the stuck in neutral issue. Given that the transmission was clearly run while 3.5 liters low on fluid by the previous owner and was problematic prior to the ZIP kit install, I decided to just replace it. I found a 42K mile ZF6HP28 online that was listed as being out of an XKR. Had the correct numbers, build date, and was marked as a 5.0 S/C transmission. Over the past week I removed the old unit and replaced it with the "new" one. The process was much more straight forward than I expected. During the install I determined that the transmission was actually from a 2010/11 Jaguar XJ and not an XKR based on the mount that was attached.

Post install I changed the pan and the fluid following the proper procedure, filling at temp while running. I was able to run through all the gear selector positions with no issue. No gearbox warning light. So all is good, right? Nope.

After backing the car out of the garage to wash it and bleed the cooling system (I change the rear cooling pipe while the transmission was out), I started it up and took it down the road and it won't shift. So good news is it goes forward and backward, LOL, but it only has one forward gear gear and the gearbox warning light is back on. It will go into all the gear selector positions (P, R, N, D, S). The paddle shifters do nothing. The scanner gives me a U3000 code which I have looked at in the manual an know it refers to the TCM. I am thinking the TCM may need to be re-flashed given that it is out of an XJ. Any thoughts from the group on next steps?

Thank You

 

I wish I could you some help after all the work you have done. I would be pissed the seller of the donor gear box lied to you; you may have bought a bad gear box.