HD wiring to headlights

[73c20jim]

Checked voltage at battery while running. 14.4v. Checked voltage while running at headlights 14.0 volts. Is a half a volt that big of a difference to do the HD headlight wiring mod???

 

[Matt69olds]

It’s easy enough to verify if it’s the ground or power side of the circuit. Put the positive lead of your meter on the positive post of the battery, the the negative lead on the tan (I think that’s the color wire for the low beams) with the lights on, engine running. Whatever the meter reads is the voltage lost on the power side. To check the ground side, put the negative lead on the negative post of the battery, positive lead on the ground post of the headlight. Hopefully the 2 meter readings equal your .4 volts. You could run the test again with the high beams. I wouldn’t worry about adding relays to “fix” .4 volt drop, that’s pretty good.

 

[Snoots]

No.
But it's still a good mod to do. The present situation wouldn't really warrant it though.

 

[77 K20]

One advantage is not running all that current thru your headlight switch in the dash. At least on mine with a long drive at night that area would get pretty hot. After the HD headlight wiring harness the only current going thru your headlight switch is just for picking up the relays.