1992 Other Chevrolet Models tail lights

Hello, what model is your vehicle? I'd do some testing at the headlite switch circuits. There may be a multiwire connector at the rear of vehicle for the rear lites, take it loose. Also take the wiring connector loose from the headlite switch, use a test lite from hot terminal at the connector to the terminal for the tail lites, with the connector at the rear disconnected, that lite shouldn't come on, if it does, maybe a short to ground on that circuit. The fuse doesn't blow till you turn on the headlite switch?