1996 XJR. Car wouldn't start; (no power of any kind) If I put it into park "hard" then sometimes it worked. I was advised to replace the Transmission Decoder. a small 3" plastic unit with a slider in it mounted under the shift lever panel on the side. This resolved the problem, temporally, now I have a new problem, the mechanic that did the work didn't do the job correctly, now the shifting mechanism is all out of whack. I called the Jag dealer in Seattle and they don't work on this older car (96) and neither do the two garages they recommended. . .So! Does anyone know a mechanic/garage within a 100 /200miles of Tacoma that I could take my XJR too?. . ."HELP"!

 

You have a 4L80E so just call a few transmission shops to see if they are familiar with it.

 

There arn't any that I can find, that's why am asking if anyone knows one

 

It's a GM transmission. There must be independent tranny shops in your area?

From wikipedia........
"4L80-Es were optioned only in Chevrolet/GMC pickups, Suburban 2500s, vans, and commercial vehicles, and the Hummer H1"

Someone has to work on the older vehicles in your area?

I used to pull the THM 3L80 (turbo 400) from Jaguar V12 and XJ-S to get repaired at a local AAMCO shop in the 1980s.
These are NOT an 'exotic' gearboxes.