Routing headlight harness a clean way?

[aod92]

Looking for some ideas on a clean way to route my headlight harness. Every way I'm running mine it looks messy. What are some of your ideas that you've done to clean things up. Thanks

[lovemy71s]

On mine right after the big plug I ran it inside the fender I guess you would say to the first headlight then I ran it under the radiator support to the other side. Left it all tucked down, mine is also a new painless kit so I had extra wire to work with. Its currently tore apart but should be back in the shop in a couple weeks to get its powerplant returned I could maybe get pics then if you needed.

[aod92]

Yeah if you could post some pics that would be great

[71CHEVYSHORTBED402]

I'm speculating, because I've yet to pull my front end, but seems the GM way is the way.

[aod92]

Originally Posted by 71CHEVYSHORTBED402

I'm speculating, because I've yet to pull my front end, but seems the GM way is the way.

My trucks been apart so long I don't remember the gm way lol.

[71CHEVYSHORTBED402]

Originally Posted by aod92

My trucks been apart so long I don't remember the gm way lol.

Yeah, I kind of figured that. Well, hopefully I'll be into my front end (currently cab) within the next four months, and I keep very good notes. Unfortunately, that doesn't help you now.

[drewbert41]

Originally Posted by lovemy71s

On mine right after the big plug I ran it inside the fender I guess you would say to the first headlight then I ran it under the radiator support to the other side. Left it all tucked down, mine is also a new painless kit so I had extra wire to work with. Its currently tore apart but should be back in the shop in a couple weeks to get its powerplant returned I could maybe get pics then if you needed.

Same here.

['68 Newtricks]

I just went inside the fender to the driver side light and then used some nice loom up over the radiator and to the passenger light. When it's all in loom, it looks fine, unless you're going for some show truck you'll never have to work on out in the cold on the road side

[lovemy71s]

Originally Posted by aod92

Yeah if you could post some pics that would be great

I will be to the farm tomorrow and see if its all still intact and I can get enough light in the storage building to get a couple pics. Its been sitting for a couple years

[FirstOwner69]

The original routing was actually pretty clean. GM ran the harness from the bulkhead plug over the top of the left inner fender (along with the washer hose) out of sight on the backside of the left fender where it was secured by one or two barbed fittings pushed through holes in the fender toward the engine. When it emerged from the front of the inner fender, it ran to the left headlight and parking light then into a plastic conduit over the top of the core support to the right headlight and parking light. The harness from the junction block on the right fender to the voltage regulator and alternator also runs through the conduit. Below are the best pictures I have available. They are before the front clip was installed. In the second picture you can see one of the barbs protruding from the wrapped wire harness just to the left of the closest white harness strap. You can ignore the red 10 or 12 gauge wire in the pictures. That is the hot wire for the optional factory camper harness.

[FirstOwner69]

Just for reference, this is how the wires to the alternator were secured to the inner fender.

[KY_GMC]

While you are at it, add some relays for the head lights. Its a cheap upgrade with significant benefits and it is pretty easy to do with a new harness.

[davepl]

Just don't use the LMC "relay upgrade" harness, it's miswired (at least for the GMC) and you have to fix it before you can use it. I mean go ahead and use it if you can find the threads about it so you know what's wrong with it, but until they get a new batch (unless they already have) that's wired right, they're a pain.

[Andy4639]

Under the fender to drivers head light then over to passenger light under the gutter on the radiator support.
Making your own relay kit is a lot cheaper and it's simple enough to do.

Using plastic wrap are the original wrap will help also.

[aod92]

I'm not really good with wires. What's the advantages of running relays?

[Sklptrljay]

Originally Posted by aod92

I'm not really good with wires. What's the advantages of running relays?

It allows smaller wiring (size/amperage) to control a relay (switch) that allows full power from the battery to a device.

In our trucks case the headlights get power through the headlight switch. It doesn't sound like much, but running from the battery, through the switch, and connections, then back to the headlights, is a pretty big power draw. Running a relay will really help the lights be brighter and save stress on the old original wiring. A starter relay is a great idea too.

[aod92]

Originally Posted by Sklptrljay

It allows smaller wiring (size/amperage) to control a relay (switch) that allows full power from the battery to a device.

In our trucks case the headlights get power through the headlight switch. It doesn't sound like much, but running from the battery, through the switch, and connections, then back to the headlights, is a pretty big power draw. Running a relay will really help the lights be brighter and save stress on the old original wiring. A starter relay is a great idea too.

Ok now you have me curious. How does the starter relay work? I did an ls swap and I have the purple ignition wire to the small post on the starter and a heavier gauge wire to the bigger post straight from the battery.

[Sklptrljay]

Originally Posted by aod92

Ok now you have me curious. How does the starter relay work? I did an ls swap and I have the purple ignition wire to the small post on the starter and a heavier gauge wire to the bigger post straight from the battery.

So right now, the purple wire is carrying the power through the ignition circuit to the starter in order to engage the solenoid and allow the starter to operate.

With a relay the purple wire only operates a tiny switch that sends power straight from the battery to the solenoid and basically bypasses the current flowing through the ignition (purple) wire.

[Andy4639]

On the head lights you would splice into the high beam wire and low beam wire at the drivers side light. You would need 2 relays one for High and one for low.
Which in the picture below you would tie the wire for high onto #86. Then on the low bean tie to #86.
Then on #87 you would go back to both high beams are low beams.

#30 would come straight off the battery with a 40amp fuse inline.

#85 would be grounds for both relays.

[aod92]

Thanks guys. I'm gonna look into doing this

[VetteVet]

Originally Posted by davepl

Just don't use the LMC "relay upgrade" harness, it's miswired (at least for the GMC) and you have to fix it before you can use it. I mean go ahead and use it if you can find the threads about it so you know what's wrong with it, but until they get a new batch (unless they already have) that's wired right, they're a pain.

Here's a good diagram for the GM Headlight relay wiring.

Originally Posted by aod92

Ok now you have me curious. How does the starter relay work? I did an ls swap and I have the purple ignition wire to the small post on the starter and a heavier gauge wire to the bigger post straight from the battery.

Here is a relay that controls the starter solenoid. If you have good clean connections and a good battery and starter you should not need it. JMHO




86 is the purple wire and 30 can be connected at the starter solenoid on the large cable.

I love to get a chance to show this.
http://67-72chevytrucks.com/vboard/s...d.php?t=655903

[Daryl87]

Going to tackle headlights and starter wiring today, so thanks to everyone for the great input in this thread. Thanks VetteVet for the diagrams!