Hello, I have a 1997 XK8 with 75xxx miles. The transmission works great except the shift fron 2nd to 3rd gear. The trans does not shift, engine revs up and goes into limp mode. If you use the left side of the J gate it will shift into third if you let up on the gas as it shifts. Much like getting a car into overdrive. You have to be old to remember that. Other than the shift from 2nd to 3rd the transmission its normal. Reverse, passing gear work normal. I get engine codes 1730 and 1734. I have replaced the valve body and filter with no help.
Last summer the transmission worked normal for a week then started acting up again.
I checked all the connections and they appear normal. Also pulled the J gate apart to check the wires.
Thanks for your time. John from Minnesota

 

The quick, easy, no guarantee answer is to change the transmission fluid.

Sounds like you have a solenoid valve sticking, a bad connection at the rear of the transmission to the TCM, bad connection at the TCM or a bad TCM, sorta in that order. I would disconnect/reconnect the trans connector and pull the TCM out and reinstall all with the battery disconnected. Still doing it; change the fluid. Still doing it; you are going to have to observe the shift process on a device like a AutoEnginuity® - OBD2 Scan Tool - Professional PC and PDA Diagnostics to see where to go and what to do.

I had a failure to unlock the torque converter on downshifts that was the TCM itself and documented by the Autoenginuity device and fixed by installing an used TCM.

 

Thanks for the info, I also suspect the TCM. I have checked the connections numerous times. I also changed the fluid when I put in the valve body. Does anyone know which TCM will work in my 97 XK8. Lots of numbers on the TCMs on ebay. I suspect the number that is important on my TCM is LJA 2401AB. Do I need to match these numbers? I found a used computer LJA2401AA. Will that work? They are hard to find and expensive. Is there someplace that rebuilds/checks TCMs?
Once again thanks for your time. John

 

Look through this Jaguar Forums - Jaguar Enthusiasts Forum - Search Results. There are a couple places that rebuild things but I do not have them committed to memory.

Unfortunately, you are going to have to match the part number and the /xxx code. I cannot believe how fortunate I was to find one for less than $100 compared to the $2050 Jaguar parts counter price. Used parts prices are always negotiable.

 

My failed TCM was LJD 2401 AB. It worked fine . . . except that it would not unlock the torque converter when a downshift was called for. Shucks . . . I thought we had a match. Yours is a LJA . . . .

Yours for the cost of shipping if you want to experiment.

 

Dear noterman,
I suspect that your ZF transmission is nearly toast. This happened to me and I had the transmission rebuilt ($5,000 if you can get a reputable shop to do it -- and you want to use original ZF parts). There is a very weak drum in the original transmission that gets torn up. There is no quick fix. Sorry about that. In my case the cost of the rebuild is about equal to the value of the car although it has only about 60,000 miles. There are two other serious issues with these cars: the plastic guides for the timing chain and damage to the cylinder walls. I've also had problems with the fuel system.

Carmudgeon

 

This all happened a very long time ago. I doubt whether noterman still owns the car as it's 6 years since he last posted in the forum.

Richard