83 Vanagon

On the way to work one morning, I tried to dim my brights, and nothing
happened--stuck on bright.  I stopped, turned off the ignition, and lo and
behold, the brights were still on.  Key off-light switch off.  I pulled the
fuses (lights out), and replaced them, brights stayed off.
Got to work and brights stuck on again.  Pulled, replaced fuses, lights off.
That weekend, van parked, brights come on.  Pulled fuses.  This time one
bright light stayed on.  Began pulling more fuses and light went out when I
pulled the radiator fan fuse.  With the raditor fan fuse and bright light
fuses pulled, the lights work OK on dim, off on bright.  I can live without
the radiator fan this winter, but miss my bright lights.  The Bently manual
has been most unhelpful.

Anyone got any ideas?

I've got some more problems if I can get this one solved, but I will save them
for a later day.  Van runs great (with the exception of needing a new
clutch--slips a little in 3rd and 4th).

Thanks.