89 to 77 front end swap-headlight harness?

[mike805]

I swapped my 89 front end (crew cab) to a 77. I'm getting around to doing the electrical and since I'm going from 4 headlights to 2 round ones, I was wondering of anyone had any ideas regarding the wiring harness? Is it simply a pigtail swap and hide a few wires or is there more involved? Thanks for the help, Mike.

[ghettoluxury]

When I did mine I used the harness from a 76, it just plugged into the connection on the fire wall.

[mike805]

Ill head to the local pick your part and see what I can find. Any other ideas if I strike out there?
Posted via Mobile Device

[ghettoluxury]

Cut the pigtails off of your old harness and re-install the correct ones.

[mike805]

So I picked up an older wiring harness out of the local pick a part but it doesn't fit. So it looks like I'm going to cut off the pigtails and use the correct ones as suggested. My only question is, what do I do with the extra wires? Since it had four headlights before do I just combine them or remove them completely? While I'm at it, I would like to do the relay upgrade as well. I obviously don't have a lot of automotive wiring experience so I'm trying to learn.
Posted via Mobile Device

[ghettoluxury]

You will need 1 ground and 2 hot per side for the headlights. It's not that hard to trace your grounds as you now have 2 on each side and the go back to eyelet on the core support.

[83GMCK2500]

Another option for the relay harness, we have a vendor that sells it: here

EDIT: Trying to find the diagram I have seen for the wiring...

Found it:

Source: http://www.73-87.com

[wraprail]

Keep in mind that pole 85 is just -Ground for the relay and does not need to go all the way back and connect to the headlight. Just run a short pigtail to the closest ground. The headlight should already be grounded.
You will only need one B+ wire and only one fuse since only one relay is powered at a time.. Just split it after your fuse and feed both relays.
Keep your fuse close to the junction block if possible. (18" or less)
The closer the relays are to your headlights the less voltage drop.
While this is true, I have not been able to notice any lower light output placing the relays near the firewall on my own truck. It has the relays placed under the dash and uses the factory wiring out to the lights. The biggest gains come from bypassing the headlight switch, dimmer switch and fuse block.