The interior lights and running board lights stay

This could be caused by a number of things. Does the car have security.? Do the lights go out after a period of time? Some vehicles have a Sensor to turn the lights on and off. Some vehicles are equipped with daytime running lights. I do not think the latter is the problem. It could just be a problem with the light switch. Please comment and let us know if the lights stay or go off after a period of time

Ground issue.

its either a bad door switch,or could be the dome override switch by headlight switch,or your interior light switch is all the way up

Most likely a stuck switch in one of the doors, usually the rear, as they are not used as often. TJ

Well, you didn't mention what the year or model of your vehicle is, so I'll just make an educated guess at the solution for your problem. I can imagine that your vehicle very well could be equipped with daytime running lights. On many vehicles, setting the parking brake before starting the engine will make the daytime running lights stay off. They will only stay off as long as the parking brake is not released.

CHECK THE DOOR SWITCHES .THEY ARE REALLY PRONE TO GO OUT ON THOSE VEHICLES.RUN INTO IT ALOT

One of the door pin switches is faulty, Interior light must be staying on and draining the battery. If you don't see the dome light staying on possibly the trunk switch is bad.

you have short between the radio and the interior light.
you need to get a diagram of the electric system and trace it out.
if you pull the fuse for the interior light, and run the CD what happen?

trace to switch (can't remember name, but it has to do with the timing of lights) and clean contactpoints. if not replace switch>

Try pushing in on the tailgate while the lights are on.