Headlight Issue

[vern350]

I'm having an issue with my headlights flashing off and on when I turn the highbeams on via the floor switch in my 1981 shortbox. Headlights are normal without the use of highbeams, they dont start to flash off and on until the dimmer switch is used to turn the highbeams on. The two blue lights on the cluster also flash with the headlights. The dimmer switch is brand new and is not the problem. Tried switching negative battery cables and alternators and no change. Battery is also new. Any suggestions would be greatly appreciated.