1969 C 10 headlights

BuckSkin wrote: ...if you have a zero resistance path to Ground, you are not going to get an accurate reading of true available voltage...

I'm afraid I did not adequately explain myself; the 'Zero resistance to ground' to which I was referring is from the Ground side of the headlight bulb all the way back to the Negative battery terminal.

In a First Approximation Theory, this is considered to be Zero Ohms; in reality, there is always some resistance, even in a brand-new vehicle. In a vintage vehicle, the actual ground path can have 'significant' (meaning enough to be noticeably detrimental) resistance.

Again, a voltage drop measurement taken from the ground terminal of the light bulb all the way back to the Negative post of the battery will tell the tale.

Installing relays to deliver maximum voltage to the headlights is an excellent way to improve lighting in vintage vehicles.

 I am reading this thread with great interest as I too am struggling to cobb onto some decent headlight replacements for the Halogens.

 My 2015 F150 came from factory with Halogen lights and after 10 years have failed miserably and after reading many articles and it seems a simple changeout to LED lights is not possible without adding additional electrical wiring and pieces,,,,

 I have talked to some owners that bought their trks new with the Halogen lights and the lights were sorry when new,,,they too want better replacements,,,,

 OH,, I would Love to get some of those old timer sealed beam headlights for my trk,,but don't think the engineers of today would allow that as no money in things that last too long,,,,