2nd Gen Non-Engine/Transmission High beam flicker

[Kissfan113]

My headlights work fine on low beam for as long as you could want to run them but when they are swiched to high beam they will work fine for 5-10 minutes and then they start to flicker on and of the guage lights the park lights and the fog lights all comtinue to work perfectly but the lights will continue to flick on and of untill the truck is parked with the lights off and will do the some thing next time it is driven any ideas on what the problem might be would be most helpful