Ah the sweet mysteries of Lucas, how they can confuse us all...I
happen to be a graduate of the US Navy "A" and "B" schools for
Electronic Technicians where we were carefully taught that current
flows from negative to positive (in the US Navy). That a "ground"
was a "ground" for the entire circuit connected to it...sounds so
simple and direct, and apparently...WRONG!!!.
Jumper wire to dim lo beam did not work, but the ground had to be
good because the hi beam (on the same circuit?) worked. Close
inspection of the ground wire revealed some broken and frayed
wires. Connector cut off, wire striped, tinned with solder, new
connector crimped and soldered on. Both hi and lo beams now
work...!!! Shoots the hell out of all those years of theory
and practice (USN in flight tech for 26 years). But who am I to
argue with success