Had my 96 xj12 tranny rebuilt and they also touched the wiring harness when told not to. After the first 10 minutes of driving it the car went into limp mode. Brought it back to the transmission shop for over a year and they never found the issue why. So i brought it to Jag and they hooked it up to the computer and the transmission could not talk to it their computer. They aren't sure what to do so they say replace the whole system for $8,000 or more. A few weird things is that coming from the tranny computer is a big red wire that looks like it doesn't belong also in the engine bay a plug that is no longer plugged in. The codes that usually show up are P0753, P0758, P0730, and P1775. When it rains the transmission runs fine no limp mode but on dry days after 3 minutes of driving once I hit a red light she goes into limp. Anyone have any thoughts before I go and replace the entire system like Jaguar said.

 

Obviously, you are not going to spend $8000 on another transmission job. Maybe your troubles are caused by a screwed up harness that they touched?

You've already spent $$ on a rebuild, hopefully that shop gave you at least some $ back, since they can't fix it. Shameful that they can't fix one of the most common transmissions in the world.

Codes P0753 and P0758 are common failure points for the 4L80E, being related to the two shift solenoids. That repair is hardly a transmission repair in itself.

You should trace the wiring and make sure you have continuity from the plug to the TCM and shifter connectors, etc. If that checks out, replace the solenoids. Worst case would be to replace the trans with a used or rebuilt. That will cost maybe $800.

 

Found where one end of the red wire went once i removed the electrical tape and found the wire they snipped just have to find the other end... Thank you for the idea should have thought of checking this stuff myself before.

 

I see, that red wire is freakishly out of place. Looks like it is replacing the orange wire that is cut, or broke! Maybe it carries on for a short distance only, providing more length, since the orange wire couldn't be spliced directly back together?

Looking at the wiring diagram, the only orange (with no stripe) wire to the Transmission Control Module is the serial communication wire, that interconnects with all the other control modules. You must find the other end of that red wire, and check and/or redo it's splice connections.

It seems unlikely that the shop would have to pull out the TCM as part of a trans overhaul. Could be that the harness was pulled too much during trans removal and the wire broke. Could be that there are other loose connections too. Speculation. But for now, resolve that red wire.

 

Shall do! Thanks!