Headlight harness for 1963 GMC truck

[RangerRex]

Hope all are well. I am needing to replace the headlight harness wiring for 1963 GMC truck. I bought the headlight harness that LMC has for that year of truck and they say works for both GMC and Chevy. But the harness from LMC has the red wire going to starter by itself and a single black wire by itself and then a double connection with two wires on it. On the 1963 GMC the light harness that is on truck has a three wire connection going to starter that connects with another 3 wire harness near the air filter that then goes to the starter. Does anyone know where to buy a light harness that will fit the 1963 GMC truck with the 3-wire connection set up? Or has anyone retro fitted the LMC light harness so they it connects into the existing 3wire connection that goes down to starter? Here is a picture of the LMC type headlight harness with connection highlighted in yellow that talking about above. Thanks.

Kevin

[RangerRex]

Here is snap pic of 3 wire plug from 1963 GMC wiring diagram that I am looking for on headlight harness.

[AZKen]

Rex, you all all mixed up and the internet has you further mixed up. There is NO 3wire connector that you show on that home made wiring diagram from somewhere. There are NO starter wires in a headlight harness.

If you will post the LMC harness part number and can answer some questions, I will help you get your truck wired. Post the instructions you received for the Harness. Where did you get the picture of the harness and where did you get the wiring diagram picture?

If I see you are not monitoring this post regularly, I will not help you.

[RangerRex]

Ken,
Thanks for your reply. The LMC part number for the Heavy Duty headlight harness for a 4-bulb GMC headlights is 36-3581. I got the wiring diagram from 6066 GMC club forum. The picture of headlight harness came from a picture American Autowire had on their website. I was looking at their site to see if they had harness and they had that pic that matched what I got from LMC, so I just used that to snap pic. The original wiring that is on the truck now, has the connector at the firewall, that runs the high and low beam wire to the grille and then also has the 3 wires that run over to the air filter that connects to the 3 wire connector. I can send pictures of that if would help. Thank you!


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[lizziemeister'sV6]

I have a suggestion if you want/need to rewire your GMC headlights - it's not a plug and play project but this will give you a much brighter lights that your truck came from the factory with. First we ALL HERE need to know what is wrong with your wiring harness - if the front wiring to your the lights are good I would pick a spot between your floor dimmer switch and the good existing headlight harness and install a HEADLIGHT RELAY that provides full voltage to the bulbs. Factory systems run all your voltage current thru the headlight switch on the dash to power your lights - if your upgrade your bulbs to any thing other than original sealed beams you stress the contacts in the little switch. Be much easier upgrading your existing harness that getting an all ready cluster mess not designed for the GMC.

[RangerRex]

Lizzie,
I agree. And that is what I am doing with the the headlight is installing the heavy duty headlight from LMC part # 36-3581. Ken, apologies on my reply back to you, I gave you the heavy duty headlight part number instead of the headlight harness part number. The LMC headlight harness I purchased from LMC is Front Lamp Harness part # 36-3160.
Lizzie, to your question, what am I trying to do. I have installed heavy duty headlight relay and now trying to get headlights lighting up. I am getting voltage out of the dimmer switch on low and high beam wire. I am loosing that voltage between there and the connector at grille for the headlights. I don’t see a break in the wire or anything obvious. The wire is old, so wanted to put new wire from firewall to connector at grille. And that is why I am trying to replace the light harness on hood side at firewall. Good question Lizzie. Thanks.


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[AZKen]

I guess you want to wire in the new headlight harness. Is that right? Are there any instructions? If so, can you post? If not, can you post pics of the actual harness you have, showing each wire and connector. Spread out, not a stock web pic.

I am a bit confused still. Did you buy two harnesses? If so, why? You do not need heavy duty. You do not need relays. Slow down. You are getting carried away and spending money for items you don't need. You can buy a whole harness for $200. For the whole truck. So what did you already buy? What headlights are you installing? LED, Halogen, sealed beam...... Do you have an alternator or a generator? Are either of those new?

I agree with Lizzie 100% except for the relays. So I guess 99%. He is knowledgeable. We can differ by 1%.

The diagram you found is full of errors. Someone took a Chevy diagram and tried to turn it into a GMC diagram by looking at the official GMC diagram and using a cad program. Also, I do not think the harnesses you bought are actually for Chevy or GMC. I think they are Chevy. These two things are what is going to confuse you. If you wish, I will help you thru this mess if you answer my questions above.

[RangerRex]

Ken,
Thanks for your reply and questions. Here are some details and answers to your questions.

- main goal: get headlights burning

- I have read on 6066 forums advantages to headlight relay system, so have installed that.

- pictures of headlight harnessed are attached to this reply.

- I bought 1 headlight harness and 1 relay wire kit for headlights. I looked at headlight harness and it actually came from American Autowire instead of LMC, like I had originally said. Pics of headlight harness and headlight relay kit attached.

- Halogen headlights are installed

- generator is on truck and it looks like it has been on there a while. Truck runs and is pushing correct voltage back to battery.

Thanks Ken for the help. And let me know if you need more details on something. The IMG_1032.jpg


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[RangerRex]

Pics attached

[RangerRex]

I have voltage coming out of the dimmer on the low and high wires. And then here at grille, pic attached, I do not have voltage.