I purchased a 1997 jaguar xj6 a few years ago. It has been sitting in my garage waiting for me to install a gear shifter. I could always put it in neutral to start it if needed.last month I installed the new shifter and now it will go into park, but the problem now is,we put the car on the road drove it for about 5 days, now, not all the time, but it will leave us stranded.turn key and all light come on but won't turn starter over. I mess with battery lock unlock un hook battery. Then it will start. Work ok for a few days then right back doing the same thing. Any suggestions?

 

Starter Relay would be the first thing to look at . Can you tap on it ? Swap with same fog light relay . Spray with some penetrating oil as the plastic relay case sticks and is hard to get out . LNA6706AA can be found at local parts store

https://www.jaguarclassicparts.com/u.../relays/relays

 

try waggling the gear selector in park when it refuses to turn over. You may not have the selector adjustment quite right, and the starter inhibitor is not being disengaged. Waggling the selector often works pending permanent resolution.