does anybody know the part no. for the 4th gear shift solenoid as my main dealer says it all comes complete with the j gate and it doesn't look like what i need

 

The shift solenoid is inside the transmission valve body not in the J-Gate shifter. You may want to take it to a trans shop and have them look at your reverse/high clutch piston as they are the number one failure item on these transimssions and can be fixed with the trans still in the car.

With a diagram of the transmission wiring you can easily read the resistance of all the shfit solenoids to see if any are bad but I doubt that is actually our problem. Let me know if you want a copy of the diagram.

 

i thought he was wrong with part i needed would the reverse/high clutch piston cause my problem 4th gear not engageing when accelerating a bit hard but ok when gently accelerating i've got no fault codes for the gearbox see my other post on auto trans fault

 

I'm not exactly sure, but that is the most common problem these Jatco transmissions have and loss of pressure due to fluid leaking from a cracked piston inside the transmission can cause all sorts of problems.

If it were me, I'd try and service it with some new fluid and a bottle of Lubegard Platinum trans additive in the fluid and see if that helps at all. Every transmission shop and re-builder I know swears by the stuff.

 

took the car out last night and no problems all gears fine it only affects 4th if you send me a copy of the wiring diagram that would be great as i have a jaguar manual from jagdocs but it doesn't have wiring diagram is that lube available over here ?

 

Here you are. The Lubegard is available online ebay should have it. Good luck!