How do you get the interior lights of a 1991 Grand Prix SE to shut off if both doors are completely closed?

If the interior lights of a 1991 Grand Prix SE remain on with both doors closed, the issue may be with the door switch. Check to ensure that the door switches are not stuck or malfunctioning; they are usually located in the door frame. You can also try disconnecting the battery for a few minutes to reset the electrical system. If the problem persists, consider inspecting or replacing the door switches.