[GuMan]

Thanks. The situation is this. I have a milli-ohm capable meter hooked up
to the ground line at the lamp socket. I have a 5 amp capable source running
at 5 amp compliance. I am measuring 0.674V total drop at a 5-amp current
with a volt meter place at the GND connection to the chassis, and the other probe placed at the lamp GND socket pin.

Years ago I had broken the factory connect point to the chassis GND on this
harness and applied an automotive grade anti-oxide compound. This
material should last as long as the vehicle is in service.

Seeing that I measure 0.135-ohms in the harness for the GND path, I suspect
this is not the issue. Also measured the path from the hot side of the socket
to the receptacle pin of the switch relay output. The condition is as good
there as the GND path.

At idle, the supply voltage at the headlamp relay is 13.6V. The voltage
across the lamp at idle is about 12.3V to 12.4V. I get about a 200mV
increase in voltage when the engine spins up just a little. There is no
noticable change in lighting for the 200mV increase. Alternator ripple
is very far below what would be considered bad.

Regards,
GuMan