I have a 2003 XJ-Sport saloon with 61,000 miles and in very good shape. My problem is that the trunk lid pops open after driving off.
I can get out and close the lid and then ...no problem. It seems to just happen just the first time I start the car early in the day.
Could this be a issue with the wiring harness @ the passenger side trunk hinge or could it be the electric relay switch that unlocks the trunk latch?
Thanks.

 

Couldn't hurt to trace it and see. I would disconnect the electric activation at the latch and see if it does it then also. After disconnecting it, I'd meter the connection for irregular voltage (ala ..a short).

 

Is it possible you are accidentally pressing the trunk button on the key fob?

I have done this a few times. I have a lot of keys in my pocket. It pops but does not open more than a inch or 2 & then when you drive off you get the dashboard warning or if your trunk struts are working well, it opens all the way.

 

Check the wiring loom that runs along the boot hinge, the wires there are prone to damage. You may be getting a short. It’s also worth checking the boot latch itself, or that you knee isn’t hitting the boot button on the dash.

 

Had this issue with more first X308. Checkered Flag Jaguar replaced the switch twice, then found an intermittent short in the wiring loom running alongside the right boot hinge.