Weird headlight problem (Resolved)

I have an unusual problem with my high beam headlights flashing. My equipment is 1994 Allegro Bus, diesel pusher. I have four headlights and when driving at night my last couple of trips, every now and then when driving with my brights, they go off for a few seconds and then come on for a few seconds. It's not like a loose wire because it is so consistent on the timing and rough or smooth road makes no difference. The dash lights, clearance and tail lights also go off at same time as the headlights and they come back on with the brights. With just the dim lights, there is never a problem.

I got a little excited the first time it happened. I was out in the country on the highway in a driving rain, no ambient light anywhere, driving about 60 MPH and suddenly NO LIGHTS. After a couple of seconds and braking pretty hard, I hit the dimmer switch and all was well. I originally thought the rain caused the problem but it still happens every now and then and it's been months since the first time it happened.

Now I'm thinking the headlight switch itself may be the culprit. I guess since all lights that go off work from the headlight switch itself, it's the logical common part in which to look. I thought I'd ask if anyone has ever encountered a similar problem before replacing parts that may not resolve the problem. OH, I haven't found a headlight relay, but if that were the problem, I wouldn't think the tail lights and clearance lights would go off.

HELP!!! Anyone????