Hi Gary, gang,
If you have the automatic headlight dimmer (that periscope thing that protrudes
from the dash top just in front of the driver) the dimmer might be trying to
switch from high to low beam (or vice versa) and the relay could be at fault.
I had an auto-dimmer on my '66 Crown. Large roadsigns had a tendency to reflect
the highbeams back into the dimmer sensor. The resulting high-low-high-low
cycling of the headlights would cause the relay to temporarily fail (perhaps
overheating or something like that) and cause all the headlights shut down.
This happened to me one time a curving mountain road. With no moon out, it was
quite exciting. Talk about adrenaline rush!
Deactivating the automatic dimmer circuit will return your dimmer switch to
manual operation.
Hope you find the source of the problem.
Good luck.
Imperial Regards,
Jay Mc Kee
1962 Crown Southampton 4-door