This little silver relay lives in the drivers door. It is responsible for illuminating your interior lights when you open the doors. Just to let you know how courteous it is, it also keeps your interior lights on for a few seconds after you close the door. If you are working on your Interceptor, with the doors open for long periods of time, I recommend taking the interior light fuse out of the fuse block. You really don't want to dig into the door panel 'cause you fried the relay now do you?