could be numerous reasons, such a bad courtesy light switch on either of the 4 doors, a grounded courtesy switch wire, or possibly an entry module fault ( when you push in the lock button, and the interior lights come on ) . Good luck
Possibe blown fuse
(from inside the trunk) check the trunk key lock cylinder. there is an electrical circuit connected to it via a cable/spring mechanism. unplug the two-wire plug to check the operation of the interior lights.
you have to go from the inside removing the plastic cover from the inner pillar from there self explanatory
Under. Hood
Where is the fuse box or fuse that disables the headlights and interior lights in a cadillac eldorado touring
the fuse box is located just below your steering wheel you have to take off that big black plastic cover to get to it but dont worry its only like 4 star screws
fuse #17 in the fuse box located under the rear seat bench
on the left side of dash board there is a little buttom push it in it will pop out turn it to either brighten dim on turn on interior lights
Check switches on doors for proper operation. they are usually adjustable.
you didnt specify year, but its time delayed electronically. Assuming they do eventually turn off, all is well. It's 1995 Cadillac Concours the interior lights, and head lights go out when I cut the car off but the dashboard lights stay on.
they are called opera lights
car door light stay on