I purchased a "Master Tow" tow dolly new two years ago. Occasionally when I apply the brake It will blow the fuse that operates the parking lights on my 2002 Four Winds RV. Recently I was pulling the dolly with my Suburban, and when I braked hard, It would blow the 30amp fuse that runs the headlamps, parking lamps, and interior dash lights. Fortunatly I had enough spare fuses to get me home. The connector on both vehicals is a 4 wire plug. Any ideas on what might cause this, or suggestions on how to fix his would be appreciated.