[xj40] Transmission Limp Mode - can't find the cause

Hello again, and “Pardon the Interruption,” but happy to post some follow-up that may help future drivers facing limp mode. Note credit is due my “master mechanic” friend/Jag enthusiast and this forum for much of this post.

  1. It was partially the hoses and leaks from them. Executive summary: still had original Jaguar stamped hoses which were breaking in my hand upon holding but looked good on the outside;

  2. It was most likely my battery storage routine; Executive summary: shutting off the battery to save it reboots the Jags entire (and entirely complicated to me) computer system apparently including some transmission (scripts/routines?). So…

  3. Buy and use a good “float” charger.

  4. Miscellaneous find: If you get a “check engine” light turn the car off. Then turn it on but only “1 turn” to display mode only and DO NOT start it. Look at the display. Take a photo. I was told the Jag technology has its own diagnostic system built-in so will tell you the code which triggered the “check engine” light. This helps the mechanic when you are past your comfort zone. Note: actually starting the car clears the code.

I hope this helps.

I continue my love and care for mine and will update on my power steering issue but just in case its summary is: bleed the air from lines by figure 8’s in a big empty parking lot and fill the fluid but not too high. I used transmission fluid but will not name it until it works or fails (as recommended product is not available though its transmission fluid is). Bought both but went with the steering fluid first. So far so good but monitoring for leaks and/or other issues now).

hello in there i have that issue with my 91 kj6 after i washed it i have since been through the cleaning and drying process my heater box had about a coffee can of water in it was flooding the connecter cable to the tcm thought i had it but as it turns out not so much looking at your approach to the problem gives me some new hope that the gremlin will be flushed out thank you for posting

Have you tried cleaning out the ac drain tubes?

t drained it thru the seams of the heater box havent found the drain tube still following the transmission limp home light issue thank you for your helpful input take care and be safe

There are two drain tubes, one either side of the trans tunnel in the footwell - pull back the carpet to see them.
Separate the lower section from the rubber connector, place a yogurt container to catch the water and send a blast of compressed air up the drain tube. I use a can of compressed air or a miti-vac hand vacuum pump although if you have a compressor handy, then …
That usually clears the blockage. If you have a LOT of foam debris etc around the evaporator you might have to repeat the operation from time to time.

thank you for that information will do!