gear box fail

[Don68500]

Hi

I have a problem with my 1999 XJ8 (80,000 miles).

It has developed an intermittent fault on start up over the last few days (corrected by restarting). The engine goes in to safe mode with a message on the dash ‘gear box fault, traction control fail and stabiliser control fail’. This now seems to be a permanent fault.

I’ve tried disconnecting the battery to reset the ECU; this corrects the problem for a few minutes.

Before and between the intermittent faults the gear box/engine ran fine.

Anybody got any ideas
Don

[Brakebuster]

hi

a bad battery can throw spurious faults, so ensure its in top condition

it has been known for the gearbox multi-plug to work loose causing problems, this is hard to get to , but can be pushed home ensuring a good connection

other than that , its an internal fault, it could just need an oil change, or it could be as bad as needing a new box

i have recently had to buy a new ECU for my 99 Sov , not cheap either way

hope this helps

BB

[joejag308]

Don its another of the "wait for developments " if the car seems to be running ok either that or get to a Jag specialist with diagnostic equipment to give it a scan.........but as BB said make sure your battery is up to the job it is the cause of so many messages appearing .......Joe

[Don68500]

A new/reconditioned gearbox was fitted by the previous owner, it’s covered about 40000 miles; the battery seems fine, however it has not been tested.
The car ran OK between intermittent fault (which is now a permanent feature) so I’m expecting an electrical problem.
I’ve put the car with Rybrook for diagnostic checks; I’ll keep you updated, thanks for your help so far.

Don

[Don68500]

Quick update:

Following a diagnostic check, the fault turned out to be the Pedal demand sensor, part of the throttle body.

A used throttle body supplied by Euro jag, fitted at Rybrook Chester cost including diagnostic test, under £300.00, result!

You can’t always believe the fault code on the dash

Thanks for your support

[Brakebuster]

result,

glad you found the fault, and glad it wasnt a huge amount of money to fix

can i ask if your car has had the TB replacement under the jaguar TSB replacement option ? this only applies to cars before 1999.....

if it hasnt, your due a free updated TB from Jaguar for your car , which includes free fitting at Jaguar , this is a safety replacement item due to the TB killing the car at motorway speeds with no warning,

you may not have needed to buy the part ??

i am currently waiting for an OBD2 lead so i can flash in my new ECM, as my car failed on emissions due to a FUBAR ECM,

BB

[phirouyer]

Same problem happened to me a few days ago. After starting, I noticed the idle was too fast and erratic. When engaging the transmission in D, I felt a jerk. Then I had several messages displaying on the dash : transmission failure, traction control failure, engine in limp home mode. I switched off the ignition, started again after a few minutes, and ... no problem. Engine gently purring, transmission as smooth and ever.
I do not know about the X308 but on my previous XJ (XJ40), the idle was regulated by an idle control valve actuated by a step motor. There were a number of factors which could affect the idle control, including a dirty airflow meter, faulty sensors or even a dirty ail filter. I am not convinced that the transmission is the issue. What could be the reason of this fast and errativ idle ? I am not convinced that a scan would give the answer.
I must specify that we have just had some very hot days, and I have noticed that heat may affect aging eletronic compoments.
Since that day I have covered a couple of hundred miles without any problem. I have checked the air filter, it was OK but I have fitted a new one. The battery is three months old.
Does anybody have an idea ?

[PeterDavisX300]

Hi Don

My first port of call, would be the MAF sensor. I would take it off completely, and give it a good spray with a strong 'Carb-Cleaner' I've cleaned many MAF sensors using this method, and this because essentially the MAF sensor is a Ford item, just like the ABS equipment, (I used to work as an Engineer on Ford cars, the Scorpio being 'MY' car, of which I've owned many, and the X300 uses Scorpio ABS) and to some peoples surprise, I use the 'thinners' smelling spray. (aye, it's thinners!) Don't be tempted to touch or try to poke anything down on the 'filament', if you look carefully you'll see the filaments are like an electric bulb, just give them a good spray. In some extreme cases you might see the filament is broken, this is a clear indicator that the MAF is goosed. Perhaps this isn't the problem, but I clean my MAF every time I service my Jaguar, I've also had the dreaded 1095 problem with the ABS, which can throw-up many other problems, I'm also able to repair the 1095 problem, with just a bit of soldering. Sometimes I wonder if anyone is listening? Never mind. This is a great site for help.

Hope that helps.

Peter