Hi I recently got a 2005 (06MY) S Type R

It was pretty cheap as it has a few issues all things I know how to fix.


However there is one issue I hadn't noticed until now and am hoping the might of Jaguar Forums knowledge will be able to help.

Fault normally occurs within a few mins of driving and 99% of the time I get the general amber warning led with two error messages "hand brake fault" and "gearbox fault", normally the gearbox and handbrake are still working fine, but once the gearbox has gone into limp home mode. So far whenever the messages are displayed an ignition off ignition on cycle clears them and the car is fine again, goes around a week's driving between events.

Each time the error occurs P1799 and P1797 are logged and sometimes (I think the time it went into limp home) P 1774 was logged as well. Clearly there is a CAN comms issue with data from the TCM(gearbox) not getting to the PCM/ECM(engine) and or the DSCM (abs/dsc)

When I was a jag mechanic (1998 to 2006) CAN faults were usually major permanent faults with no start and often no ability to get the car out of park, get the park brake off or even the electric steering lock off.

Once in a failed state it would probably be easier to find, but I would also be stranded, So I would like to try and diagnose before its gets to that state.

I'm unsure if its a poor connection / harness issue (water inclusion) or a faulty module (hope not ££££) so if anyone can help that would be great.

If any owners have any ideas on the cause, particularly if you have had the exact symptoms yourself I would be really grateful to hear from you.

Also if any Jaguar techs are out there who fancy a challenge I'd be really really grateful to hear from you. I have limited IDS access (no oscilloscope) and 2005MY wiring guides

Thanks for listening

Paul (Tame Technician)

 

Hi Paul,
Those CAN codes will tell you which connectors to check and it is not a bad idea to do so.

Whilst you are doing that give the battery a full 24hr charge, as you may know , the slightest drop in voltage can cause all sorts of weird problems.

I'm sure someone with more knowledge on your MY will be along shortly.

 

Commiserations on having some of the rarest codes

Any work been done recently before this came up? Any accident?

I wonder if a connector has been damaged or knocked loose, or wiring trapped during a repair or accident.

 

Thanks for replies.

No no accident repair as far as I can see, and I'm pretty good at spotting these things.

Previous owner has done some work on the car, the plugs have been changed and I noticed to get the coil cover off the harness over the back of the N/S bank is moved and not clipped into the fur-trees correctly. Doesnt look out enough to rub but worth a look and it has had a gearbox oil change (i dont know if they did the connector o rings) trying to find out.

I will be having a close look at the underside when I get it on a ramp in a couple of weeks but for now the weekend plan is to disconnect the main engine harness connector (the one with the 10mm bolt through it) and check for water / corrosion. If I can get under do the same at the gbox connector, but this may have to wait until on the ramp.

Played up on the way home yesterday, fine today.

 

Maybe the electrical connector in the gearbox slightly out? They've been in there to change the oil...

JTIS may have details for troubleshooting those codes.

 

FYI

Battery full charged and tested ok. And is only a year old, also most of the time fault occurs while driving so by them battery voltage irrelivant really.

Now all that said this moring ign switched on, amber light and hand brake warning displayed. So i didnt start the engine and read the codes.

P1797-00 in PCM .

Also there is a known issue with the key in switch, the locking column motor cycles a few times some times when you but the key in. Its logged B1352 and b1352-64 for this.

I dont think the key in switch can have an effect on CAN comms as CAN switchs on with the key in pos 2 not key in, but if anyone knows different please shout it out.

I will keep this thread updated as and when stuff happens incase anyone else has the issue at a later date.

 

Have you measured CAN voltages to check that? The ICM is live and also has CAN and one of its terminators so I'm a little surprised if it doesn't wake up with key in.

Most faults along these lines are worth troubleshooting where work's been done (trans) or any other suspicious things (column motor etc).

CAN's fairly robust so you're probably looking for a loose connector or maybe a dry joint. We see those occasionally on ABS and ICM.

 

No, Not yet will try when I get a min been a long time since I done this, do you know where the easiest connector is to get to. I'm guessing J gate.

Agreed.

The key in switch sound unlikely but the more i think about it the more likely it sounds.

 

Firstly, Hope everyone had a great xmas.

Just wanted to Update the tread.

Well the Gearbox Fault display didnt happen for a week, then happened 2 days in a row within a few miles of home, seemed to be after going over speed bumps, but then I got the park brake fault again with the car still on the drive, so harness wiggle / chaif seemed less likely. Checking with IDS showed weather Gearbox or Park Brake faults were displayed it was always P1797.

Got the car up on the ramp at work and had a good look at the harness from the rear of the gearbox up towards the engine ECU. There is very little visabilty or access here, but what I could see looked ok, no chaifing or obvious damged insulation.

I unplugged the connector at the gearbox to look at the pins and it was heavily contaminated with gearbox oil. I guess it needs a new sleve / connector. However as a temp fix I have cleaned it out with brake cleaner and contact cleaner, then a blast with a 90psi blow gun. Since doing this I have not had a repeat of the fault display and so far so good, no P1799 or P1797.

I am keeping everything crossed at this point - if its really is only that, i'll be over the moon.

Some pics to follow when i get a min. Working 28th boooo.

 

Hi....I've been plagued by this fault code (p1797) with the addition of the dash board going mental for 6 seconds then going back to normal......I also get a whole host of abs and stability warnings and the hand brake warning, all for 6 seconds then it goes back to normal. she drives fine during these episodes most of the time but sometimes she goes mad and its as if she's jumping through the gears for no reason.......I've replaced the dash (recommended b the indi that tested the car as he said it was the fault) but to no benefit and changed the connector on the gearbox but have not been able to road test the car as it failed the MOT and ive not had the time to fix it yet..........id be VERY grateful for an advice, I love her but if its a major electrical fault it might be game over.........thanks.

 

That all sounds like a chafed wire / power problem.

Car details?

 

im im Bingley, west yorks............do you know of anyone that could find the fault.......as a pose to charging me a weeks wage to tell me they don't know!!!!.........ive had a local garage that employs a new lad that suppose to be a jag trained EXPERT but ive got socks older than him and he didn't even know the 308 has a separate ecu for the gearbox!!!!!!!!!!!


he claimed to test the wiring and said he found nothing but they don't have the full jag computer testers so I think he just looked at the loom and didn't see anything obvious...........That will be £120 plus v.a.t scanked you very much sir...!!!!!!!!!!

 

Er, 308? Is this not an S-Type??? You're in the wrong forum if it's an X308.

I haven't needed anyone for electrics and would hope to DIY but Jagfix The Jag Specialist is a new independent Jaguar specialist based in Doncaster (Doncaster) is supposed to be good and maybe N & S (Wakefield) Independent Jaguar Specialist in Yorkshire 01924 831140 but again I don't know what they may be like on electrics - or X308 if that's what you have.

However, tricky faults are a pain and 120+VAT is not a shock - though I'd want someone who knew what they're doing.

 

I think you found it with the transmission oil in the electrical connector.
Hope to hear back that was the problem and everything is running correctly!
.
.
.

 

The problem with these intermitant faults is you cant test the wiring, or at least you can but the test will always show everything is fine, unless you happen to be doing the test during the 6 seconds when it plays up.

As you say, X308 doesnt have the gearbox ecu inside the Gearbox like X350 & s type so the connector that seems to have fixed my issue is not likely to be the cause of your issue.

You need to know which modules loose comms and investigate the can wiring from one to the other.

We are going back a long time, but when I worked on x308's the ecu box could fill with water the terminals get corroied, worth a look.

 

Any follow up on this? I've had the mysterious "gearbox fault" followed by the trans limp mode, only to have it go away upon a restart a few times. I always had the same p1797 code, and the trans feels fine when it isn't in limp mode. I'm guessing mine is probably in the same condition although the STR has been parked for the better part of two months due to pretty much constant snow.

Did yours ever return?

Thanks in advance,

George

 

Since cleaning the oil out of the gearbox connector I have had 6 weeks of trouble free motoring, with no warnings.

That said it did say park brake fault (a result of the same fault code) once a week or so ago. I presume, as I didnt replace the connector or o-rings, there may well be oil still getting in there and as the ammount builds up I expect the fault to return. But for test perposes cleaning worked great.

I have a few pics of the connector, but tbh they are not great quality. Will try and get them up at some point.

When I was a Jag tech we often had CAN issue cause by broken/ corroied wires in the front end harness (behind the front bumper) The twisted pair of CAN wires were from the Engine ECU to the ABS ECU. It is relativly easy to repair/replace these wires, finding the break is the hard part.

While I feel your description sounds exactly the same as mine I would check the gearbox connector as soon as the weather there allows, Just bare in mind It is definitely possible that all these P1797 are caused by the beging of a broken wire, but until it brakes permanantly you wont ever be able to find it.

once found will look similar to this
http://www.interworldna.com/images/pico/corsa-fig3.jpg

also see
Wiring harness corrosion behind front bumper