X350 XJR gearbox problems - any ideas please?

[Ian350]

Over the past 3 years the gearbox on my 155k mile 2003 X350 XJR has been going into limp home mode. It used to be 1 trip in every 10, then 1 trip in ever 4, now its every trip - usually after about 15 miles. A quick switch off and restart used to clear it but now that doesn't work unless I pull off the road and leave the car locked for around 2 minutes or so. Its just getting worse.

Two different garages, one a Jaguar indy, have looked at this a year ago or more and although both tried a couple of things it was clear that they were just guessing.

I have my own code reader and when it happens I always get the message - P0705 "Transmission range sensor "A" circuit (PRNDL input)". Any ideas what the fix should be and how much it would cost please? I really need it fixed now, not just another guess!

Thanks

[8bit]

Does it drive OK? No thumps, noises, etc? Changes gears as it should?

The place to look for help would be jaguarforum.com, I had a quick search there and found this for a start - https://www.jaguarforum.com/showthread.php?t=30811...

Has the transmission been serviced?

[Ian350]

It drives perfectly, no bumps or thuds, its very smooth. Gear changes occur at the right time. Oil and filter were changed about 40k miles ago.

Thanks for the link - I've tried googling it but can find virtually nothing.

[P700DEE]

Have you tried a ZF specialist? Jaguar indy's probably know to change the oil but are not experts on this very common 6 speed box that was fitted to loads of different cars. Gearbox specialists get all those jobs your usual indy can't handle and the good ones know their stuff and pay for the proper kit to talk to ZF in Germany. I used Dartford transmissions but you should find similar closer to you if not near them.

[sjc]

First things first .. is the battery 100%? And I mean 100%? One tiny voltage drop can throw up all sorts of weird and wonderful issues on these all over the car.
Then check the Earth studs.
Then the gearbox electrical connector that can sometimes get covered in oil apparently.
All cheap fixes to start with, good luck.

[Ian350]

P700DEE said:

Have you tried a ZF specialist? Jaguar indy's probably know to change the oil but are not experts on this very common 6 speed box that was fitted to loads of different cars. Gearbox specialists get all those jobs your usual indy can't handle and the good ones know their stuff and pay for the proper kit to talk to ZF in Germany. I used Dartford transmissions but you should find similar closer to you if not near them.

Thanks, good idea - found a gearbox specialist and have e-mailed them.

[Ian350]

sjc said:

First things first .. is the battery 100%? And I mean 100%? One tiny voltage drop can throw up all sorts of weird and wonderful issues on these all over the car.
Then check the Earth studs.
Then the gearbox electrical connector that can sometimes get covered in oil apparently.
All cheap fixes to start with, good luck.

Thanks for the suggestions. The battery is less than 2 years old and these problems started before then. Also its on a charger when we go on holiday. As regards the earthing points I did have trouble with these but had them re-made at last year's service.

The problem was noticeable in the early days especially when wet so I had the electrical connectors cleaned up and protected. That seemed to work for a while. Maybe oil has got in there now though.

[sjc]

Well best of luck that's it's something easy, and let us know the outcome, always handy!

[cornershop]

I had my X356R fluid flushed yesterday and the mechantronix seal was found to be just starting to leak, which could be the cause of yours.

The whole flush cost me £630 incl new pan, ZF fluid, and above seal.

Of course a drain, refill and would be cheaper.