Each door frame has a plunger-type switch at the rear of it which switches the interior dome light on when the door is opened. In order to gain access to it, use a screwdriver to take the two screws out of the switch house and then push the plunger assembly out of the door frame, and ensure not to rip open the gasket behind the plunger. To be on the safe side, check the back of the switch to make sure that the wire is not damaged, is totally tightened and not corroded. Installation This should be reassembled with the original gasket should it be in good condition or a new gasket should be installed and the screws should be tightened up securely and check that everything is functioning correctly.