Sorry if this post is much of a repeat of the original but feel the problem has been going on so long that any feedback although much appreciated and helpful has been lost in a sea of maybes and continuous testing only to reach the conclusion that somewhere within this cars veins is an electrical fault/intermittent awaiting discovery. Obviously i have exhausted all component checks and gradually working through wiring harnesses. As the photo's show the initial faults looked fairly textbook but The mystery of the 1643 code is where it gets stupid. The car has gone from no j gate lights and non start to intermittent j gate lights but starts every time! just in limp mode and occasionally no faults everything normal until driven up the road a few hundred yards.even when jgate red indicator is not lit. Now i am about to check Tcm harness to engine harness expecting to find a connector to the engine harness but looks to be hard wired into the engine harness? Not a problem can still fault check but guessing any new wiring that may be need will have to be spliced in accordingly. Hopefully this will finally resolve the issue as apart from this the car has no other faults including engine that is silky smooth. When it dose behave it runs very well and since changing trans filter,sleeve and rubber seals and fluid the gear change is near as good as it gets. So i guess any further ideas are most welcome as after this i will seriously be forced to think about giving up as no room for a garden ornament and another car lol

 

Have you followed pinpoint test E on page 2852 of the Jaguar workshop manual?
(As indicated on page 2845.)

http://jagrepair.com/images/AutoRepa...M-Workshop.pdf

Mellow

 

Yes i have and was inconclusive

 

So looks like i finally nailed the issue!! The pin in the tcm plug were very loose fitting but didnt realise when i was doing the atf and filter change and only found out because because i closed them up a little to have everything back to normal but not for long lol so went back under to double check and realised that the sleeve i replaced is clearly not in as far as it should be and oil had seeped onto the contacts causing the the shorts hence tcm losing contact with ecm. The original sleeve was seated closer to the casing so silly mistake but for the sake of dropping the pan again at least i now know the original cause of the problem or problems depending which way you look at it.

 

Well very well done! So glad you found it and fixed it. I also had a bit of a fight when replacing the sealing sleeve but I was warned how important that connection was and kept at it. It does not help that it is almost inaccessible to get at too!

Surprised you could get the retaining clip installed inside the pan with it poking out that much?
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I notice that you have a park brake fault. Have you been able to pinpoint that and if not several of us have found the problem and the work around.

Tom In Dallas/Plano
05 S-type 3.0 121k

 

Just an update of the original problem! After a few days same fault has reared its ugly head again with same fault codes? Seriously this car is out to mess with my head and has achieved it lol. Weather hasnt help in getting any further since it started again but i am convinced this is total power fail to the jgate/ tcm as when it works it drives normal. Still intermittent fault and i now suspect the primary fuse box to be the issue so will start there when i can. The reason being is the p1643 fault code says can bus connection fault but then if the tcm dosnt power up the only fault it can report is can bus fault as the tcm is unable to send fault codes without power. Impossible almost to fault check an intermittent wire fault but trust me ive been through just about everything including modules, earths plugs sensors etc. chasing my **** because of a dammed fault code the possibly dosnt exist. Jesus!!!! and they reckon electric cars are the future lol

 

In post #4, one week ago, you mentioned a loose contact and problems with the sleeve seal. After correcting those issues, how much have you driven the car?

When you said the same code had returned, my first thought was one (or both) of the previous faults had returned. In other words, maybe the seal was better, but still not 100% and it slowly started leaking again. Or maybe the suspect contact worked loose once more.

To put it another way, you fixed it once and it held up for several days. Given a chance to spend your time and money, I'd suggest revisiting that recent work before digging deeper elsewhere. It seems you were hot on the trail with the two repairs you did, but for reasons unknown they did not hold up.

 

I am afraid to say that the sleeve not being seated correctly would certainly have caused a problem or the problem or could have but after starting again with it i.e. drain oil, sump off and reseat the sleeve was a success and not further leaks on numerous test runs while the problem remains to be intermittent? The connector was a red herring it seems and on a long day fiddling around while someone is seated with ignition on watching the jgate light confirms this issue has got to be power related as opposed to can bus on the common sense approach of no power no means no faults to be read from tcm except a remedial fault from ecm say unable to connect to tcm. and with tcm harness wires checked off as good the problem is further along towards the main power distribution hopefully at primary fuse box! The power relays all checked out ok and at this point i have lifted the front fuse box and yet to remove the primary. It may seem like clutching at straws but complete power disconnection is more likely than can bus fault going on this logic. Will update as i find i guess but intermittent faults are no joke due to there nature and beginning to think fault code readers exist only to confuse it lol but hopefully i will be proved wrong

 

Please break posts up to make them readable!!

The J-gate lights are basically for info. They are lit (or not) by the module. If that module didn't get the network packet(s) to turn a light on/off it wouldn't matter and it's unconnected with the P1643.

However, it might be a sign of a wiring issue - you'd have to study exactly how the wiring is done (see Electrical Guide).

The codes PDF shows all the causes of P1643 and is the main thing to use. Again, for wiring see the Electrical Guide.

P1643 doesn't seem to be due to power/ground issues - unless someone knows otherwise.

 

So are you saying that if the red jgate indicator light is not lit then the tcm is still getting power?

I have been using the wiring diagrams since the start of this problem and also read the values for p1643 and carried through with tcm wiring tests to no avail. Im no expert on this subject but if something isnt get power then it explains why my fault code reader isnt picking it up hence the ecm calling the p1643 code.

This was proved when the car momentary started working normally long enough to connect to the tcm and that also showed no faults! so to me it seems clear and logical that if the engine is already running when this power out happens then it will continue to run until it is switched off but will not restart as the tcm is not active so unable to complete the prestart checks.

I appreciate your help and can conclude this is definitely a wiring/connector issue but i am now having a hard time finding out where the issue is and to be honest no amount of reading diagrams seems to be helping anymore.

 

There are lots of modules, the JGM (J-Gate module) could be faulty or badly connected and/or so could the TCM.

So, the J-Gate lights not working as expected can mean either the TCM is OK but the JGM isn't seeing the data or that the TCM isn't OK - you can't tell from the light(s) being wrong.

The TCM can respond to lots of OBD-type packets, including ones about errors. (The JGM can't.)

If the TCM responds to any packet it obviously must have power.

So far, the errors make it look as though it does have power but may not always have a reliable network (CAN) connection, though it would help immensely if you had a tool which could be prodded to do a kind of "hello are you there" message on demand (the TCM is willing, it's at CAN address 7E9, in an elm327 you can use atsh7e9 and so on).

 

I was under the impression the jgate received signals from the tcm to enable it lo light up whatever gear it was in, although the white illumination power comes from the instrument cluster? may be wrong on this but just what ive read.

Interesting point about the tcm could be powering up but no can signal! but as i said before a bit confusing when the car only starts when the red indicator is lit. Not sure what you mean by this as no power is getting to the tcm
hence no messages.
(the TCM is willing, it's at CAN address 7E9, in an elm327 you can use atsh7e9 and so on).

I currently use 930i and it dose read the tcm as other modules only if they have power and the tcm dosnt. so to date have not found any breaks in the can bus through testing and the power to tcm is switched on by ignition 2 at which point i should have visual confirmation being the jgate should be lit dependent on whatever positiopn it is in. Have tested trans harness through the diagnostic port test in the manual and proved fruitless and would have liked to have disconnected the harness to do this but unable to source the connector to the engine harness.

I have read some folk have found the jgate circuit board to be contaminated or broken to produce similar faults so maybe worth pulling apart although unsure where the circuit board is situated within the jgate.

 

The JGM board is just under the top of the J-Gate I think. It gets messages from PCM (aka ECM) & TCM.

If doubting it they must be readily available from breakers.

 

Cheers, but if i doubt the jgm module then i just as well chuck money at all the modules at the moment as i havnt a clue now and pretty cheesed off taking things apart to test it only to find nothing and then out of nowhere it decides to start!!

Never consistent enough to give you the slightest clue and to be honest im done with it. To go from a perfectly running car to this in less than a day is not a good advert for the reliability of the electrics in these cars, dont get me wrong i expect problems with old cars but this is poor. I guess another one bites the dust

 

You can't really complain about the electrics in that way as yours is the only one with such an issue despite the cars being 14-23 years old.

You do sound to have a wiring problem, even if you can't find it, sadly.

 

Yes im sure i shouldnt be complaining when ive had and still own a vehicle over twice the age which still drives without these issues! Its easy to sit and quote this and that but not so easy when your trying to get your head around stuff most garages wouldnt bother with. then to realise a simple wire issue writes your car off. But hey who am i to complain.

 

hey andy! I saw the other thread where youve found the broken cable under the fuse box. Which was it? As i have intermittent j gate lights off and p1643 and tran fault erorr. Thanks 😎