I have had the 3.0L XJ350 2004 for the last 12 months its been a great car but I have been getting the gearbox fault light come up.
I had the same problem on the last jaguar s type 2.7L.

I booked to get the car reprogram at Jaguar in south of france I was told the car would not take on board the new program and I would need a new gear box this is what i was told with the S type 2.7 at jaguar Monaco.
They still charge me 190 euros which was for nothing I felt cheated.

after more information it sounds like the ecu and the valve body needs to be change after speaking to gearbox specialists I was informed because the ecu can not be programed and it only fault is going up hills the drive around town no problems and is sports mode no problems i can drive for months at a time all good.

any feed back would be much appreciated also i looked in to a new ecu valve body and the price is around 900 pounds.........all ready to go newly programed..........
its not a hard job to change

 

If you've changed car you'd help yourself by changing your signature.

 

I can't help much myself except to say it is possible to change individual solenoids in the valve body but of course you need an expert for this.

I suggest you have a word with Chris in the UK (Doncaster) who is a highly regarded Jaguar independant.

His business name is Jagfix

 

I tried to change my signature but with no luck I have added some more photos etc.

 

I will follow up on this lead and thank you.
I was quoted 900 pounds for a complete ecu and valve unit this is a exchange.

matthew

 

Is the correct amount of fluid in the gearbox ? Too little might result in the box not getting any on a steep hill.

 

I check the oil about 6 months ago when I did a service and front breaks............
al good.......................

 

Was the oil seal on the TCM module connection leaking, and was this replaced when the fluid was changed ?

Early cars eventually started leaking at this location and a newer seal was put on later gearboxes, and is backwardly compatible for earlier cars. It could be you have contamination of the multi-pin connections at this socket due to transmission fluid leakage. This would then possibly prevent a TCM reflash. I very much doubt the gearbox has failed, they are exceptionally reliable.

The other possible aspect is the mechatronix unit within the box can have inter oil passageway leaks due to the seal between it and the box failing. It then needs removing and replacing with a new sealant. I have seen reports on other forums for BMWs etc that report this, but not here. Same gearbox, though.