I have an 03 x type that i bought in april. Have done quite a few things to it to make it road worthy and am coming close to getting it done. Finally as im about to take it for a final test drive i get a gearbox fault and now wont go into drive. If i put it into 2nd then to drive it will go. It goes through all of the gears as it should. I wouldnt be too worried about but now when im driving on the highway it seems to take a very long time to get up to speed. Takes a distance of about 2 miles before it hits 80 mph and pedal to the floor. Will only rev up to about 3k rpms doesnt seem to want to downshift out of overdrive. I pulled a health report and have a p1780 code for d4 switch malfunction. I know that the shifter and linkage are a known problem with these things and have no problem replacing it. I just want to know if these 2 issues im experiencing are related.

 

It's not a problem I did have before, but if you google "P1780 Jaguar", you get e.g.:

• Replacing the transmission control switch
• Repairing or replacing the TCS harness
• Replacing or repairing damaged TCS circuitry

 

Yes im seeing that as well with the transmission control switch and i believe that is in the j gate shifter? Shifter is working at the moment but requires me to go into 2nd first before itll go into gear. I dont mind having to replace it to fix that issue but if its still going to have troubles getting up to highway speed then id rather not right now.

 

I might be wrong, but would have expected to find a transmission control switch on the transmission. I could tell you, where it is on Ford Fairlane '97.
So I googled again, and found this:
https://www.jaguarforums.com/forum/x...switch-193573/
Look at the picture showing the "Neutral safety switch". This would be equivalent of the switch I am thinking of at Ford Fairlane. The one on the Fairtlane likes to play up. Thus, just maybe this is your culprit...

PS: Just FYI: That "switch" in the transmission of the Fairlane is called "inhibitor switch" and it kind of looks similar to the one in the picture of the link above. Not that similar as being interchangeable, but similar enough to let me think that if the inhibitor switch on the Fairlane is prone to failure, maybe the one on the X-Type is as well...

 

I did see that as well when i googled it. Although i didnt give it much thought since i have no issues starting the car. Will definitely have to look into that.

 

Also: If the fault lies indeed in the area of the "Neutral safety switch", consider that it may not be the switch itself, which is faulty, but the wiring connected to it - or more likely the connector. Try cleaning the connector pins with a wire brush and then spray CRC 2.26 onto both sides, or similar.

 

Im going to go through everything this weekend. The switch, the linkage, the shifter.. see if i can pinpoint the issue. The thread you sent earlier had basically covered those 3 things as well as some wiring diagrams to go with it.