Without getting into too much detail my 05 XJR has another transmission fault, stuck in 3rd gear again as far as I can tell.

Now I know this has been discussed several times already, but I can't find a thread that asked it in this way, so - what exactly would the car do if someone were to fit a T56 trans to the car? I know the TCM and ECU are linked and the dash would light up like a Christmas tree, but what would actually happen? Would the car be rev-limited and in a forever limp mode? Would all of the other electronics cease to function? Has anyone ever tried this?

I love mostly everything about this car but I've always hated the ZF in this and my old STR. And with it crapping out again I am about to sell this thing for whatever I can get and put a down payment on a manual Chevy SS - the right way to do a sports sedan IMO (but lacking in the looks department when compared to an XJ).

 

I've found the ZF to "just work" and do everything I want but hey YMMV apparently.

Forget trying to fit any other trans. Cost tens of thousands if you can even find anyone to try it.

Your current problem may or may not be the trans but it sounds like you don't care to keep the car so move it to someone who will.

 

I don't think there is a reasonable way to do this. My Jag is my first automatic transmission vehicle. While its a good shifting automatic its not a manual.

You started this post one day too late for
https://bringatrailer.com/listing/1999-bmw-540i-17/

and a month too late for
https://bringatrailer.com/listing/2017-chevrolet-ss-5/

 

One more in Pougkeepsie
https://hudsonvalley.craigslist.org/...954476604.html

 

I think that maybe I let my frustration run my mouth a little too much at times. I would love to fix the trans but from 10 years+ as a member here and as the owner of 4 Jags I get the impression that as you said, the trans "just works" when it wants to, and when it doesn't it is usually replaced. I have gone through every fix on this site myself (reflashing, shift solenoid, gear oil flush, pan replacement, sleeve, etc.) and every time the issue is fixed for about 1000 miles and then returns. My feeling is if I have to replace the trans anyway, why not put something in that doesn't inherently have all of these problems.

That being said, I think that my rant may have clouded the original intent of this post: what exactly would happen if the TCM doesn't see the trans there? I see many threads saying "don't do it, the TCM and ECU are linked", but I can't find a thread that tells me what the exact ramifications of this action would be.

I don't particularly care if the dash says some crazy stuff or if the light is on if everything else does what it is supposed to. I am thinking that functions such as the ABS, SRS, gauges, climate control, radio, etc. wouldn't just shut off because none of that happens during a transmission fault or during limp mode. And to the best of my knowledge the car is not rev limited during a transmission fault, or at least it didn't appear as such when the car was in neutral. So if the only thing that happens is that my dash turns into the 4th of July, I would probably do the swap, maybe not with a T56 but I could find/fabricate something that would work.

 

In any case, what I am proposing is a crap-ton of work.

So you mention that the problem may not even be the trans. Please share this knowledge with me so I can try some stuff before making any hasty decisions.

I have read about a few issues that may cause transmission issues. The car has a brand new battery, so I doubt it is a voltage thing. I have also seen a theory that it is linked to a misfire, but I don't feel the car running rough and my OBD reader has not pulled up any stored codes whatsoever, let alone a misfire. Do you have any other suggestions?

 

I appreciate the help in locating a new vehicle, but I think that in my frustration I made some statements that may have caused people to miss the point of my thread, so let me clarify.

I stated in a previous post that I am the owner of 4 Jags. I think that this statement should imply that I love Jags enough to tolerate their quirks. Every morning I go outside and look at my car (any of them) and say "damn, that is a good looking car". And then I get in the car and say "damn, this is a good looking car". I can go on, but I don't think I need to to make my point.

Everything about the Chevy SS (mechanically and electronically) is exactly what I am looking for in a car. But when I look at one I say "It's a car. It just looks like a car." I know what they are, and I do get excited when I actually see the rare beast on the road, but if I didn't have knowledge of what they were, it would just be another car. And then everyone else sees it and says, "hey, nice Malibu".

My two main Jags are a 2005 XJR and a 1998 XK8, 14 and 21 years old respectively, and people still to this day say, "wow man, that's a nice car". They are timeless and exquisite, and that's why we are all here on this forum and that's why we put up with the Jaguar nonsense and try as hard as we can to keep these cars running. And I hope no one on this forum pretends that they don't know what I'm talking about; these cars are comparatively very difficult and expensive to maintain, and it seems as though the engineers had their heads on backward while designing them (anyone who disagrees with this statement has either never worked on the car themselves or never worked on any other car for a point of reference; please objectively try to justify a valley hose or aluminum suspension components fusing to steel bolts, or the ZF trans for that matter, I can go on but I won't).

Anyway, while I'm sure that my current string of posts has made me look like a jackass enough, I just want to know what happens if the TCM/ECU does not see a transmission.

 

There is a rather simple test. Unplug the TCM and any other electronic connections to the auto trans, and see what it does.

Presumably, when the ignition is turned on, the ECU goes through a self-check for all components and modules status. When it finds the TCM missing or otherwise unresponsive, the engine will not start. Even when the silly gear selector jams on these and the car can't confirm the car is in Park, the engine will refuse to start.

Adapter plates, physical mounts fab, driveshafts, all doable. The real challenge with manual swaps into beautiful modern cars with great engines but crappy autos, is tricking the ECU to think the auto is still there. Reverse engineering the expected signals, and then building the electronic component to send them when expected by ECU is the real challenge.

 

What fault codes does it throw up, and what did your auto transmission shop tell you about them and the cause of your problems ? My first X350, a 2003 had similar faults to yours cured when a reflash was done, and also the TCM socket sleeve on the transmission was replaced and the area cleaned up. After that I never had any more problems apart from a hard shift occasionally. There can be a problem with the ZF mechatronic unit inside the box whereby the seal between it and the gearbox fails so the fluid pressure goes to the wrong set of gears. This is rare and these boxes are generally very reliable.

My second X350 (actually a 2007 X358, with the restyled front and rear), was totally fault-free transmissionwise.

 

A misfire you can feel is HUGE on a modern car. Those you can't feel can easily upset the trans. (Lots of other engine issues also can.)