Headlight wiring question

[jbgroby]

Ok here is a longish question in two parts. I don’t think I’m going to be able to explain it right the first time so I’ll need some help. First the basic and background:

I’m using the E-Z Wiring harness 21 circuit set up. I will mount new halogens as the lights (whether I need to follow Jolly’s relay information I don’t know yet, since all the wiring is new and better than the old factory stuff I may not need to?)

I mounted the headlight buckets and in the process of laying out the wiring main truck lines. I have two wires going to the headlight system; one which splits into two wires marked Left High Beam/Left Low Beam and the other set marked Right High Beam/Low Beam. The wire are bare at the ends.
The outside lights have 3 prongs and the inside have two prong. Because I’m a a novice (once I do something I usually pick it up) But It seems that I’m sort a wire or two.

I was thinking of buying the premade setup for our trucks from one of the various truck places so I would not need to make up the harness. If I do that do I simply tie the “new premade harness” into the two wires coming from the junction block? Any help appreciated.

Jake Groby

[FreakyMalo]

You'll be happier if you use a relay setup. You'll have brighter lights and less electrical load on your switch. And you can wire a diode between the relays to keep the low beams on when you're using the highs. The two wires from the new harness would trigger the relays.

[markeb01]

Hi Jake, you might want to take a look at this thread, since it’s also done on a 1960 GMC. It includes relays that are hidden under the radiator apron, so it still looks stock when all put together.

A new aftermarket harness would be a very simple solution to connecting your headlights, but it’s important to know if the manufacturer upgraded all the wiring to 14 gauge wiring, or duplicated the original 14 gauge high beam, 16 gauge low beam with 20 gauge ground wires. If it’s a duplicate of the original it’s substantially undersized and will provide the same lousy performance.

http://67-72chevytrucks.com/vboard/s...EADLIGHT+RELAY

[chopper john]

just buy the pre made harness for the bulbs and then plug high and low to the end. done.

[jbgroby]

A new aftermarket harness would be a very simple solution to connecting your headlights, but it’s important to know if the manufacturer upgraded all the wiring to 14 gauge wiring, or duplicated the original 14 gauge high beam, 16 gauge low beam with 20 gauge ground wires. If it’s a duplicate of the original it’s substantially undersized and will provide the same lousy performance.

http://67-72chevytrucks.com/vboard/s...EADLIGHT+RELAY[/QUOTE]


Mark,


Do you know IF any of the truck shops/parts places have a better wiring harness? I have a feeling that if I call they will not be able to tell me. OR are you saying I get the new harness then upgrade to the wirte up you did?

Thanks
Jake

[markeb01]

Hi Jake, if you can determine a manufacturer that makes their headlight harness with all 14 gauge wire, I’d say buy a new harness since it would make for a very easy installation. I always intended to do all my own wiring, so I never did any research to find out what wiring is used in aftermarket harnesses.

[fleetsidelarry]

Originally Posted by jbgroby

I have two wires going to the headlight system; one which splits into two wires marked Left High Beam/Left Low Beam and the other set marked Right High Beam/Low Beam. The wire are bare at the ends.
The outside lights have 3 prongs and the inside have two prong. Because I’m a a novice (once I do something I usually pick it up) But It seems that I’m sort a wire or two.

Jake Groby

Jake, either I haven't yet had enough coffee or just am missing something. the wires you describe above, where do they originate in the harness? is this a full chassis harness or in-cab harness? the way your wires are labled doesn't make sense to me but I am not familiar with aftermarket harnesses

as you probably already know from looking at the relay wiring schematics, the headlamp circuit should begin with a single power feed from the light switch going to the dimmer switch which splits the power out into 2 wires, one for the high beam circuit and one for the low beam circuit. once thru the bulkhead, the lowbeam and highbeam circuits should each split into a left and a right, and for your 4 light setup, the high beam wires each split again. your headlights are correct, the 3 prong provides for a high beam and a low beam, the 2 prong is high beam only.

maybe your wires are simply mislabled and should read: highbeam L & R and lowbeam L & R

[jbgroby]

Not your fault...

The E-Z Wiring has all the wires coming from the fuse block. The main point and questions is the following (I'll probaly mess this up so bare with me)

There are two wires coming from the block one for the high beam lights and one for the low beam lights. each wire then splits into two. (left High Beam - Low Beam) then one set for Right Hign Beam /Low beam. each wire is bare at the end.

I'm confused (normal state) as it seems I'm short wires? Each bulb has two term. and the high beam has three. Either I have to make these up or would it be simplier to buy the pre-made harness and simply tie into the two wires coming from the fuse block. I'll try to post some pictures later.

BTW IF I do that I'll need to make up the relay set up that was tlaked about.

Oh I forgot I'm running a one wire 12v Alt.

Sorry for the goofy way I'm explaining it.

[FreakyMalo]

Your low-beam bulb has 3 terminals; low, high and ground. The high beam is only high and ground.

The headlight harness contains the feed wires and a jumper from one bulb to the other for the high-beam. Ground goes to the headlight mounting plate. It's not that difficult to make and you could use heavier wire to handle the extra amperage that those halogens will want. The thread that markeb01 posted has all the answers regarding the relays.

[jbgroby]

OK, IF we guys can figure out a way to add the relays I also figured out that someone woudl have made it up witht he upgraded wiring. Sure enough LMC sells the unit. PAge 41 of their catalog CBE.47 $29.95 THey sell two different systems, Single Bulb and Dual Bulb

Single Headlight Cat# 36-3580 @$29.00

Dual Headlights Cat# 36-3581 @ $29.99

These include the relays and are relay to plug and play. I'll call and confirm these are correct for my truck. Been a long day fig. all this out.

http://www.lmctruck.com/icatalog/cbe/full.aspx?Page=41

[jbgroby]

Ok I nice pretty box from LMC came in today with eh new upgraded wiring harness for the heavy duty headlights.

The setup seems easy All I need do is connect the new wires for the headlight to the sockets in the new hardness.

I'll take pics when installed. once it is laid out and all works, I'll cover the yellow with tape or paint, that color will stand out badly.

[FreakyMalo]

That was easy!