do i have a faulty headlight switch?

First, i dont have autolamps or daytime running lamps. It is a 2002 Ford Crown Victoria, Police interceptor. All of a sudden when i go to turn the key the headlights, taillights, and all exterior lights come on. but know when i leave it over night something is draining the battery all the way down. if i unplug the negative side of the battery when i park for the night and then hook it back up before i try and start the car in the morning everything is fine, but all the lights still turn on for a few seconds then they turn off unless i use my headlight switch to manually turn them on or off. if i unplug the headlight switch and leave the battery hooked up the battery doesnt drain overnight. any thoughts, please.