Originally Posted by Frankie the Fink

Its a good practice to wire high-draw items through the relays as a matter of course...then the old wiring is merely providing a 'trigger' source for the component and not the full current required. For one thing, no matter how good your wiring may look, its age is causing increased voltage drop, -- another argument for a new harness. The 14.1V your alternator puts out may be just 11.5V at the headlight connector with 50 year old wires.

Read up on headlight relays on the Mad Electric site for examples:

http://www.madelectrical.com/electri...adlights.shtml

To wit, the pros on here aren't telling you to get a new harness just because of the Bubba fixes - age is a factor.

The second thing is that such high-current items' main power feed needs to come off the horn buss relay which will let the voltage regulator "sense" the proper current requirements and adjust alternator output accordingly AND make your dash gauge read correctly.