C4 corvette headlights
 

Recently we noticed on our 1994 LT1 Corvette that whenever you start the car all the marker lights Run perfectly, however, whenever you turn the headlights on it turns all the marker lights off and the running brake lights as well. When you turn the headlights off the running lights and brake lights come back on. Does anybody have any idea where to begin trying to fix this problem? Any and all advice is greatly appreciated.