Hello,
I have a 2000 XK8 that I bought recently. It has only 41k miles, but is a piece of junk, abused by a previous owner. I'm trying to fix it and save it, because it's a beautiful, great car, potentially.

The problem was originally that the car wouldn't start sometimes, as it would have a transmission fault. I took it to a Jag specialist. They said it was the shifter assembly, as a previous owner had messed with it, shaved a part of it off, and re-attached it by jury-rigging it, and that the shifter parts were not syncing with the computer chip that controls starting the car. I paid a lot of $, replaced the shifter, but no difference, problem happened the very first time I tried to start the car. I took it back to the shop, then looked further, and found that it was the switch on the transmission, I guess the next link in the chain. That was taken off the factory rivets and screwed back into place, so it was messed with as well. This seems to have fixed the starting problem, but then it threw a transmission code of some type (within their Jaguar proprietary software) that wasn't allowing the switch to talk correctly to the transmission computer control module. They swapped my computer with a dialed-in test unit they have and everything checked out okay, so they said I need to replace the transmission computer. They cannot find another transmission computer, out of production.

The questions I have to the group:

1) They say the car will start now with the new switch, so do I even need to worry about the trans computer?

2) I'd like to make the car right and replace the computer, as I want everything to work, if I can find one, either way. The shop gave me the part number, LNC2401EB, but there are suffixes when I did a quick search from some well-known parts suppliers, such as LNC2401EB03 or 04. Is on more "right" versus another?

3) Are there any other part numbers/computers that would work, or is it very specific to a 2000 XK8 only?

4) Does anyone know of any suppliers that may have this part?

Thanks for any help and responses. -Chris

 

The TCM in your car is easy to replace, but I'd be a bit concerned that a jag specialist cannot locate one. So, you may want to determine

1. what scanner codes are being thrown that indicates to them that the TCM needs replacing
2. lift the carpet in the trunk/boot on the left hand side and find a sticker with your TCM part number/software version (should be something like LJE2401AB/XXX) to confirm. That will give you the three numbers of your programming version (XXX), but you should find them easily on ebay for less than $50. For example, depending on what you find in the trunk,

https://www.ebay.com/itm/JAGUAR-TRAN...gAAOSwOxJeK3uO

or

https://www.ebay.com/itm/1999-2003-J...0AAOSw0qFdX~Vq

Good luck with it.

 

Thanks for the reply! As I remember, they mentioned 3500 as a code.

I don't have the car back yet (getting it tomorrow), so I will check the TCM then. The Jag shop says they can't find LNC2401EB, not that they can't find any TCMs. Yes, I found a lot of them on ebay as well, but not that part number. One of my questions is that I don't know if I MUST have LNC2401EB, or will ANY XK8 transmission TCM work, such as the one you mention? If an old XK8 TCM will work, then I'm in good shape, but I do not know. I'm still a newby to the XK8.

Cheers,
Chris

 

Codes should begin with a letter (like P1747), so I'd ask for a list of the remaining codes when you pop by.

On a replacement TCM, perhaps something else will work (there also may be a vendor who will fix your TCM, depending on the problem), but depending on what you find in the trunk and the codes(s), I'd also figure out what isn't working now before I replaced anything, especially if you are able to drive it off the repair lot without issue.

There are also other options for locating a particular TCM such as salvage networks in the US and UK, and specialist jag suppliers, ebay just happens to be fast and direct.

 

I agree with crbass:- ask the shop for the actual codes that have been pulled.

The no-start is much more likely to be around the shifter than the TCM - they rarely seem to give trouble anyway, hence they're cheap second hand.

The label in the trunk that crbass mentioned looks like this:



In my car it's on the rear RHS of the trunk - you may need to take the spare out to find it.

Good luck!

 

Thanks! The shop did say the car will start now with/without the "good" or "bad" TCM, so not really sure what to think. I'll ask them more about it and try to get the codes and generally more info. They could be just trying to rip me off, too, although with the prices they charge, I know they are already ripping me off!

I'll check the sticker when I get the car back tomorrow, then go from there. My biggest issue is still whether or not I can use a different TCM than the one told to me by the Jag shop. If so, then it's no problem to find one with a slightly different part number.

Cheers,
Chris

 

Thanks again, everyone. I got the car back. The Jag shop said that the TCM needs to be replaced because occasionally, the TCM and the R&I Transmission Rotary Switch don't speak together properly and the TCM thinks the trans is in a different position that it actually is, and it won't start sometimes. The Jag shop gave me "LNC2401EB" as the TCM part number, but once I looked at my sticker, as you all mentioned, mine reads "LJD2401AA/003." I didn't get the codes, as they said they needed to go back and find the tech and look it all up. I just wanted to get out of there. Not sure where the Jag shop got the "LNC" #, but it doesn't match the one on my sticker. Maybe the TCM on my car is the wrong one, with this "LNC" part number? Since they replaced the R&I Transmission Rotary Switch, is it possible that I would need "LNC2401EB" in order to match the Rotary Switch? How can I get to the TCM computer to see the part number on it? I know it's under the triangle plastic piece by the firewall, under the hood, but, then where is it? Under the large black box? Thanks again for your help and suggestions.

-Chris

 

Yes, under the black box with 4 torx screws holding it. It's the first thing in the box, standing vertically. Big connector, easy to remove. It will not have the /003 part on the TCM, but should have the LJD2401AA (or something) part.

You probably should go have codes read somewhere or acquire scanner since the explanation seems odd. The scanner will be helpful in your 'new life' anyway. Was it shifting properly, and did it turn on?

"TCM random communication issues" here seems like an explanation in search of a problem without anything else. These modules are pretty robust with wide temperature specs. Randomness seems more likely switch/wire related (or maybe remotely possible, the wrong TCM but you'd think the symptoms would be less subtle) ...

 

Thanks. I'll look at the TCM tomorrow and check the number there. I do have a regular scanner and I did not get any code before I took it to the shop. I'm going to check the codes again tomorrow as well. The Jag shop mentioned that they have Jaguar proprietary software and that they saw the problem and implied that it is outside of the normal scanner you can get at the auto parts store. I don't know for sure what the deal is; the service manager was not the best English communicator.

It shifted properly, but about every third cold start, it would not start at all and give me a bunch of faults on the dash display. After 10-15 minutes, it would allow me to start it and it would drive fine.

I don't know how much the Jag shop is lying to me; I know they lied about some things, but I'm not sure about this. I'll check the TCM, the scanner, and maybe not worry about it unless I have another problem. Thanks!

 

Quick look at ebay, this will likely work

https://www.ebay.com/itm/JAGUAR-TRAN...sAAOSwzzBeTLyY

LJD2401AC/003 might work too, but I'd really figure out if you need one at all.

 

I see your VCATS is in the spare wheel well. These things seem to be stuck in all manner of random places. Irrespective of what descriptions you've been given, your car came out of Brown's Lane with a LJD2401AA/003 TCM.

What crbass said. The TCM relies on the rotary switch to tell it what's going on.

To access it, lift off the RHS false bulhead cover, and remove the four screws circled below. Hopefully they will be torx, but you might find 'tamperproof' cheesehead bolts. A tad harder to remove, but not much so:



lid removed:



...although, again, it is probably not at fault.

What was the dash telling you?

 

It could be your lucky day ! I had an 98 ish XK8 in the shop for diagnosis a few weeks back, with a similar issue.

It started by going limp when it was moved from the Auto side of the J Gate to the manual side, it then got progressively worse so you intermittently got limp/gearbox fault even moving from P to D or N/R. But then sometimes it would all be just fine!
It had recently had a new gearbox and a replacement TCM put in it, not sure if that was to try and fix this fault or not. I know that the J gate had been apart several times to try and fix it.

Looking at the scan data (on a JLR dealer laptop) it all looked fine and it showed it moving smoothly through the gears, putting out the ones and zeros to to indicate what gear it was in. - Just like your shop said- it all looks fine on the Jag scanner.

The clue came when I saw the indicator lights on the J Gate occasionally just flicker slightly on change. Knowing that the lights were driven from the CAN bus output from the TCM and ECU and not the J Gate, I put my scope on the P/N output from the transmission selector switch at the ECU (P/N goes to the ECU the rest go to the TCM), it should switch 0-12v from P to N like this



However just occasionally it would do this



That's a 30ms glitch, enough to confuse the ECU into setting all the warnings. I checked at both the ECU and at the selector switch plug to eliminate the wiring. Replacement selector switch from a breaker and all good.

 

Thanks again for all the replies. I got to the TCM in my car, and it is the same part number as is on my VCAT sticker, LJD2401AA. I don't know why the Jag shop would recommend ONLY that other part number, LNC2401EB, unless that is the part number they have on their "test" TCM, and for some reason they are clueless about other part numbers, or they are just trying to find that one so they can rip me off by claiming it's very expensive. I've lost trust in this shop, going to try another one next time.

Anyway, decided to just leave everything alone for now, until/if I have another problem. To answer someone else's question, when this problem initially started, I would get Trans Fault, Traction Inactive, and ABS inactive, 3 messages total, then the car would not start for 10-15 minutes, then it would "wake up" and start with no problems.

Today, I drove the car around, started it up about 5 times with no major problems, except once in a while the Trac disabled message will flash for maybe .3 of a second when I'm starting up, but then everything is fine. Most of the time, no fault messages at all. Maybe something like this is what Wight8 is describing, just a blip, but enough to quickly flash a fault message. I will keep your post in mind if I have any future major problems, but so far so good (good enough, I'd rather have no flashing or fault messages). Don't want to spend any more money on it for now, spent a fortune on these repairs, of which I got little in return.

All your messages were very helpful and I've received some educating as well. Thanks again! Cheers!

-Chris