Well ive been through everything i can think of with my cars problem (previous Posts) and cannot find where this fault is originating from! How crazy can it be when a car starts and drives then dosnt for no known reason that anyone can fathom.

I wish i could afford to just chuck money at it replacing modules just in case it might be one of them but they all check fine when it decides to work including the gearbox but when its dosnt the only other way is replacing the entire wiring system and it wont be happening. Ive never been scared of fixing any car and this one is no different but the electrics have taken the best of me and although the car is top notch condition wise it is good for nothing.

I may buy another one day as im assured this is a rare problem although its doubtful. All this hassle from a full jag serviced history low millage car?

 

Perhaps this has been suggested in your prior posts, but have you checked the boot to see if there's evidence of water or condensation around the battery and main leads to the starter motor?

Corrosion or a poor connection can cause what you're describing.

 

Hi, Yes i have had the boot completely empty and no water leaks or even any signs of there having been any in the past.

Not sure how condensation would effect the starter motor from engaging? The jgate red in gear illumination dosnt come on with ignition or rarely so unable to crank and p1643 says can bus or worst case dead tcm. Cannot locate faulty can bus wire as yet and from what ive read could be any amount of issues apart from can bus then others say different on other post ive read.

Ive pinpoint tested everything related circuit wise for this fault and when the jgate lights up it all works as it should? The only module i cannot communicate with is the tcm but on occasion it decides to work then this is possible and all faults can be removed?

Found another post on a different forum with exact problem on a 2003 model same gearbox and he even tried another box and that didnt solve the issue and never posted if he got to the root of the problem but carried out all the usual checks and just about everything i have covered.

Thing is its one thing fault finding but then the nature of how the wiring system is built leads you to end up with a car in a million bits and still none the wiser. As said i give up now as life is more important than banging my head against a brick wall. Very much a shame as the last car i spent this amount of effort on rinsed me of cash and then the only reason i got rid is because it needed more than i could afford but at least i knew what the issue was when it went... This car however is just a kick in the nuts.

 

In the case where it's CAN related, I'd make sure I could use a meter on the CAN wires concerned at will (possibly by adding some extra wiring), then when it won't crank check their voltages.

(Not much extra wiring & twisted per the spec)

(I might use a 'scope but it doesn't sound necessary.)

 

Is the TCM mounted forward and to the right of the JGate assembly like it is in the X's?
If so, there has been some issues seen by X owners of TCMs getting some moisture finding its way on to the TCM harness and connector via the heater assembly.
Possible you might have something similar if S-type heater assembly is similar and TCM placement also similar.
Could cause CanBus errors.

Long story short, water entering cabin air intake due to lifted plastic scupper shield or blocked drains, goes into heater box, drips onto harness and creates internal corrosion of connector pins actually inside the TCM.
That has caused some members to have TCM communications errors due to pin to pin electrical conductivity.

Here is a thread that has some photos of what you might see. post #31
https://www.jaguarforums.com/forum/x...-187973/page2/
If that sounds plausible, remove and open the TCM module to look inside.
You can clean connector and PCB with a small stiff bristle brush using IPA, Meths or a non residue electrical contact cleaner.
Note any possible blackening of solder connections to the PCB, as solder breaks down when exposed to water going dark and scaled.

 

No, it's inside the trans, well insulated.

 

Hi JagV8,
Thanks for the clarification......I know that little gremlin has caught a few out on the x's.

 

Are you still getting the strange fault of continuity between CAN+ and BATT? IIRC, one of the pinpoint tests had you measure resistance between the two points and it was supposed to be greater than 5K ohms, or something like that. This is an unusual fault, so that's where I'd suggest concentrating any efforts.

I get it, you're done with the car, but I'm thinking of the next guy who buys it. Send him here and we can continue to walk him through troubleshooting. You've either got a bad module somewhere on the CAN bus, or a fault in the harness. Neither is a showstopper.

For the fault (low resistance) between CAN+ and BATT, you can monitor this directly from the OBD port under the dash. You don't even have to open the hood, crawl under the car, or disconnect anything. Just connect your meter between pins 6 and 16. You can connect your meter directly, or you (the next guy) can spring for an OBD breakout box. Here's one inexpensive version on Amazon:







What brand/model meter are you using? I highly recommend the next guy gets a digital meter with an automatic min/max record feature. Most digital meters have this feature nowadays, except for some very basic models. You set up the meter as normal and then press the min/max button. When the value changes, the high or low peak is recorded, plus a chime sounds. This is incredibly handy for chasing an intermittent fault, such as when shaking down a harness. It lets you work by yourself versus having a helper watch the screen for an easily missed spike.

One previously asked question, but I don't remember seeing an answer: What happened to the CAN+/BATT fault when you disconnected the harness to the transmission? Obviously the car won't start, but I'm wondering if the fault cleared.

 

Gave up and came away from it for a while karl, Better to take a breather and a fresh look at things.
I did join the uk jag forum just to see if anyone had had similar problem but to be honest it was just full mostly of folk not willing to read the post properly or not at all and joining at will suggesting stuff already explained?
On the upside came up with some ideas relating to the power side of things that could be promising as it seems ive been chasing this elusive can bus fault code in a literal sense when really i dont thing it is anything to do with it directly.

Weather permitting i will get back to it soon! I did put it up for sale and a guy was quite keen on having it but couldnt go through with it in the end as much a pain it is the second hand car market in the uk has gone crazy high so thought i would better stay away. Better the devil you know!!

 

Issue now solved permanently! Should of ignored the fault codes completely and trust my instinct more on this occasion but hey im no expert.
It was a power issue but nothing to do with can bus although it dose highlight how crazy it can get.

All running good again and can now spend time doing some proper mechanics like changing out the valve cover gaskets etc.

 

So, um, glad to hear you found the problem but please elaborate. What exactly was the “power issue”?

 

This turned out to be a broken wire in the engine harness! between fuse box and tcm.
Instead of chasing it down i replaced and re routed a new cable from fuse box to tcm harness and this sorted out the problems. Deleted any remaining codes and all faults after a run have not returned.
Gearbox runs smoother than ever with no jerky changes and epb works as it should.
Only a matter of time before something else arises but i dont think anything could be as frustrating as this last problem and learned more than i ever wished to about the electronics of this car.

 

Which wire?

 

The broken one.

 

hey im having the same issue. Could you or someone please point me to the coresponding pins/ cable? Thank you!!