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I decided to start a new thread since the road trip thread should be about the road trip
Joe (Harrier) posted a well done lighting diagram. I did my headlights a bit differently. The drawing I did comes from the circuit in a kit I bought, which turned out to be a waste of money. I ended up making my own harness anyway, using very little of the harness I bought, just the connectors and a few wires.
The kit I bought used an existing headlight connector to connect to the relays, then used new connectors on the headlights. I drew it up that way, but I simply removed the old connectors and used quick disconnect connectors from the existing headlight wires. I used 12AWG wire (because I had it), and I only drew one headlight, I just connected the hi and lo beams together and grounded to the inner fender.
I did purchase 6v halogen headlights and the difference in color and brightness is dramatic. Let’s fess up, many of us are a bit north of 60 and need all the help we can get at night.
As for grounding, I’ve found many grounds in my truck are not solid. The best way I’ve found to test is measure voltage from the device being grounded, and the battery ground (+ in my 6v system). It should read 0 or very close to it. I found some grounds measuring close to one volt, that’s not good.
And yeah, I’m an electrical engineer, but I earned my degree many years ago, we couldn’t actually do any real electrical work until that guy Benny Franklin shocked himself with a kite, and my diploma was written by monks because there were no printing presses.
I don't know who you got your kit from that was not good but what made it not good?
I used a kit (LMC) on my 81 F100, 12 volt not 6 volt, and was night and day different. I added it shortly after getting the truck on the road after a 4 year cab off frame rebuild so I knew grounds were good.
Did you do a voltage drop on the head light power side not just the grounds?
That is where the relays shine as it is pulling power off the battery and the old head light cirit is just used to trigger the relays.
If for any reason that relay kit goes bad I can unplug it from the lights and the tie in plug and return back to the factory setup.
Dave ----
I don't know who you got your kit from that was not good but what made it not good?
I used a kit (LMC) on my 81 F100, 12 volt not 6 volt, and was night and day different. I added it shortly after getting the truck on the road after a 4 year cab off frame rebuild so I knew grounds were good.
LMC is great so I didn’t want folks to think I was disparaging them. It didn’t work for me because I have a 6v system, and the headlight connectors wouldn’t fit through the holes in the inner fender. I basically used their schematic and a few parts of the harness.
Did you do a voltage drop on the head light power side not just the grounds?
That is where the relays shine as it is pulling power off the battery and the old head light cirit is just used to trigger the relays.
If for any reason that relay kit goes bad I can unplug it from the lights and the tie in plug and return back to the factory setup.
Dave ----
That’s a good question, and I do think there was a voltage drop but I didn’t measure it because as soon as I opened up the headlight I saw that the old cloth wires were rotted and had many bare spots.
That said, if you have a bad ground and show a voltage, it’s effectively a voltage loss anyway.
As for the effectiveness of the relays, what it’s doing is removing all the 70 year old connections, switches, wires, etc from the circuit. So you’re correct, get the voltage direct from the battery with new wires and connectors.
You are right any part of the path that is bad, ground, makes the whole path bad.
It would have been nice to see just where it was bad LOL.
Question, would the 12v LMC relays work on your 6v truck?
Dave ----
I learned a ton about ground planes servicing and building tube type guitar amps. It’s critical that the ground plane is solid, or things can go haywire.
No, the LMC 12V relays need at least 9V to trigger (I tested them) so I purchased the TO relays at only a few $ each. The only complication was the LMC connector didn’t fit, so I just put spade connectors on.
Just in case anyone is doubting my wisdom for replacing the original headlight harness (I’m sure no one is) here’s what it looks like after I touched them. They didn’t look like this until I touched them, then the cloth jacket just fell apart in my hands.
The moral os the story is...don’t trust 70 year old wiring.
