To solve the problem of an inoperative interior light, it is necessary to check the location and position of the interior light switch, and make sure that it was turned on. Then ensure the battery voltage and ground at the bulb socket, you should find both present and change the bulb. When there is no voltage, check the interior light fuse to voltage and replace battery voltage (when missing or blown). In case of the lack of ground, check the door switch contacts and clean or repair them accordingly. To maintain an interior light that will turn on and off, check a damaged bulb filament and replace it when necessary, check the bulb and socket of the corrosion, cleaning or replacing where necessary. Also, seek out loose, broken, or corroded wires and terminals and repair where necessary, and test the functionality of the door and light switch, replacing it where necessary. When the inside light is extremely low, then examine the bulb and socket, cleaning or replacing them accordingly. Troubleshoot low voltage at the positive terminal on the bulb socket or a bad ground; trace the wiring to verify loose, damaged, or corroded wires, terminals, repair, and test the door and light switch operation, replacing them, as needed.