Jaguar 1997 xk8 brake lights come on by themselves after 20 mins.or so.Even if car is locked or not.

ck these sites.......

https://www.google.com/search?q=1997+XK8+Convertible+top+not+operating+properly&newwindow=1&sxsrf=APwXEdfOPppygmW8ejwhnjfXMEviAHPQ_A%3A1683048270803&source=hp&ei=TkdRZPK8LvmD0PEPptqU2Aw&iflsig=AOEireoAAAAAZFFVXnaTqBf1xoRl5P3l-65_gtsQiL4k&ved=0ahUKEwjym8ayk9f-AhX5ATQIHSYtBcsQ4dUDCAo&uact=5&oq=1997+XK8+Convertible+top+not+operating+properly&gs_lcp=Cgdnd3Mtd2l6EAMyBQghEKsCMgUIIRCrAlAAWABg8RpoAHAAeACAAaoBiAGqAZIBAzAuMZgBAKABAqABAQ&sclient=gws-wiz

Question edited to add maker.
Question moved to model category.

It appears to be a known issue. Videos that may help.

https://www.google.com/search?q=1997+Jaguar+XK8+convertible+top+will+not+raise

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Batteries that are on the way out will give false malfunction signals. Replace your battery before doing anything else.

It is located under the panel in front of windscreen

You've done most of the steps I would have so far... Now use a meter and trace the wires backward. Sounds like a broken or chewed up wire along the route backwards. Also try a separate wire with power to see if you can deliver power to those lights. If they work, albeit temporary for the test, you grounds are good. If one works and the other does not, then THAT ONE has a ground loss. In any case, you have it narrowed down, and I would hope that by now you may have your answer. Let us know so we can share our knowledge with other readers. Thank you!

it should be the door selenoid causing the problem it has the linkage attached to it and would give you the problems you discribe

this is an electrical part and most probably needs to be replaced , but if it does not go into the lock it self ( Lock is closed while boot is open ) , you need to open manually with a screw driver and then close your boot

check your lock relays located in the interior fuse panel. Sometimes the actual connections to the fuse block can come lose and the relays wont work properly. My 2000 silverado did the same thing till i bent the pins on the relay for a tighter fit.
hope this helps

go to autozone have them scan it and then clear it record the trouble code and then clear it another option is disconnect the battery both positive and negative and make a jumper wire between the 2 terminals make sure that you disconect the battery very importan

your brake switch, the one that activates rear brake lights has probably failed. Press brakes, have someone see if brake lights turn on, if no then it is a brake light switch problem.