OK, one last ditch effort to figure this out before enlisting the local Jag dealers (expensive) (poor) help. I've got an ongoing transmission problem with my 2004 XK8. It will display Transmission Fault internittently and shudder when it does so, but when I stop and restart the car the fault disappears and it drives fine! Occasionally the speedometer instantaneously dips to zero and then back to normal also! Will also get a Cruise Not Available fault displayed. Used to get a DSC Inoperative fault displayed along with a clacking from the rear driver side wheel, but that seems to have stopped showing up for now. It doesn't seem to be a hard transmission failure since when I restart the problem vanishes for a while, seems to be electronic. Is there a way to check or replace only the transmission computer (I assume it has one); if I take it to the Jag dealer will their diagnostic service get it to that level? I suspect they will just say replce the transmission since the car has 150K miles on it. Any insight would be greatly appreciated!

 

Welcome to the forum buckhow,

I've moved your question from General Tech Help to XK8/XKR forum. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

prob not the issue but have you had the battery load tested? Weak battery can cause some strange electronic issues with these cars. The trans issue may be bigger than that but you saying if you turn the car off and back on and it is gone for bit could be something that simple.

 

You should get the fault codes read and report back. You can have them read for free at an Autozone or Advanced Auto.

My guess is you have a defective transmission output speed sensor, or an intermittent connection between the sensor and the TCM. This sensor seems to be a common thread between your faults. If so, this is a simple repair.

The fault code will help confirm.

Then take the car to a good independent repair shop that services Jaguars. In general, an Indy would be cheaper and more familiar with an older car.

 

I am presently dealing with a transmission issue. When driving the car felt like it was lurching at 25, 35, 55 & 70 with no codes then it provided a code and was able to pull off to the side of the road. Took the code reader cleared the code and drove it home, all was good. Next day drove it and got the same code with a can code and it was dead on the side of the road. The codes were electrical code #3 shift solenoid. Made several checks and removed the transmission control module and had it tested by ASI and they found a problem and fixed it. My checks involved checking the continuity on every lead to and inside the trans no problem found so I reinstalled the TCM and gave it a short run and came up with the same issue. I presently have a new transmission valve body to install and awaiting the TCM from ASI because I wanted to be sure it was not damaged again.

Check your codes and see what you have. If you have no codes the purchase a pocket size OBDII code reader plug it in and drive the car and it should capture any codes that are temporary and post them on this forum. If you want to you can send me a note and we can talk about it.

 

Thanks for suggestions! OK here's the latest :-( Purchased a used 2005 XJ8 transmission with 74k miles, local independent installed it and a rebuilt torque converter. Then he realized it had to be reprogrammed to work, so to resolve he took the frame holding the old TCM (I guess) off of the old mechatronic valve body and swapped it onto the replacement used tranny. The tranny now worked, but still had the same transmission fault codes/cruise unavailable/stumbling/speedometer blips/abs lights/DSC inop lights. Except now it had a RESTRICTED PERFORMANCE fault! Took a chance it was the ABS that needed fixing, so sent it to the only shop that said they could fix 2004 modules, they resoldered all connections BUT couldn't solder the connector pins since they are apparently PRESSED on only. Driving it without the ABS module resolved the transmission fault issues and the car shifted and ran fine except for the resricted pefromance. Got the ABS module back and it ran excellent for about 2 days, unntil I called my friend to brag how nice it ran and it appeared fixed until it threw the transmission codes while I was on the friggin' phone!!! Now back to square one except now I have a restricted performance issue to resolve too. Can it be that the old TCM (I think it is the TCM on the plastic chassis attached to the mechatronic valve body?) was the problem and the repair guy put the problem part back into the replacement transmission? If so, can I get the TCM that he deinstalled from the used tranny recoded to my VIN? If so, how?

By the way, new symtoms or problems ... intermittent drivers airbag light, intermittent restricted performance (bank 2 lean code) and right blinker intermittently blinks fast.

Having way to much fun with this ghost rider!!! Maybe a Chevy next if I can get the codes fixed so I can sell it!!!

 

Check the rear wheel hub on the driver side. There is an ABS sensor there at a fixed position. It is able to do its job because of a ring with teeth in it, and that ring rotates with the axle. There have been reports before of that ring coming lose (no longer solid with the axle) and giving false readings. My understanding is that this sensor tells the TCM what the vehicle speed is. Without that input, all kinds of errors are thrown, both related to the transmission and the ABS. Try and move that ring. If it is anything other than completely solid with the axle, you will have identified the root cause of your troubles. While there, check the ABS sensor itself as well as the harness connector to be sure. Best of luck, keep us posted.

 

That's what happened to my 2005....the Ring snap in two giving out transmission issue code that points to TCM and ABS cruise not available....one shop told me to cwap the Tranny (he said the valve body must be leaking) to the tune of $3500 luckily I was hesitant and talk to other Jaguar specialist until one simply ...just said " let us have a look and we'll need one day" 3 hours later they called and said..."Your Jag is done"...and I asked them " what do you mean?" he said we fixed it ..it was the ring....That was the best $400 repair job I've ever had.

My symptom was similar to OP's drive it for about 30 minutes then the dash lights up and the tranny went into limp home mode.

 

Thanks, I will definitely check that. Don't know if I mentioned it before but I have heard a creaking coming from that drivers rear wheel for over a year...guess it may be the ring creaking? Hopeful one more time

 

Thanks everyone! Well, checked the speed sensor ring on the rear left and sure enough there is play, and it appears to stick when the wheel is rotated by hand. Guess I wasted a lot of money on a replacement tranny ... the other one was probably fine. Man, can't find a dependable Jag repair shop ... even the dealer just pops and swaps, starting with the most expensive it seem!!

Ordered a replacement ring, and will try to replace it. Is it possible it is just a fastener and the ring is just loose? Is it a difficult remove/replace? Anyone have any videos or pics?

 

Glad to hear you have found the problem. I sincerely believe this is the root cause of the problems.

For repair, I have never done this job on this car so I cannot help you directly. I would encourage you to search this forum for clues. FWIW, I seem to have the best results with google directly, with search terms like this:

This way, it searches this forum, specifically for your car, with whatever search terms you want (here "rear axle").

Best of luck, keep us posted.