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Headlight, brake light wiring harness? easy to replace?

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dasanii19

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Oct 11, 2006
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Location
NV
1976 k5 blazer-

I see that on my firewall is where the headlight/brake light wiring harness plugs into. Is this a cheap and easy replacment? what else plugs into that unit on the firewall besides the headlight/brake lights?
 
it is a easy replacement. just find one about the same year and swap them out. 89-91 had a different plug . i made my own for my 75 clone using my factory 89 harness it was not hard. i think the horn might also be on it. next time i'm up in my parts area (junk pile) i'll check i might have one for a 73-79 around. why do you need to change it?
 
I want to replace it because my headlights flicker when I move the wires around.

I just unplugged the whole headlight harness to check it out, the terminals look really grimmy and I dont know how to clen them up? WD40 and a toothbrush maybe?. I would also trace the whole harness down looking for any bad connetions and fixing them. Do you think this should fix the headlight flicker? If not, id like to just buy a brand new stock headlight harness, I looked on LMC but all I see is upgrades and not a stock replacment.

Any ideas guys will really help. Im right in the middle of this as we speak.
 
Nobody knows where to get a new stock headlight harness for a 1976 K5 blazer? :confused:
 
Use contact cleaner to clean the contacts, it usually comes in an aerosol can, they have it at the parts store. For a new harness, you might want to try the junkyard. I don't know if anyone sells stand alone harnesses for headlights and taillights. Put an ad in the "parts wanted" forum, someones bound to be parting out a truck with a good harness.
 
If you are going to use contact cleaner, make sure that it is safe for use on plastic or you will ruin the connector.
 
AZ79K5Project said:
Make your own. Napa sells the wire connecters that goes into the plug. I updated the harness to handle the better headlights.

The factory connectors are packed with dielectic grease.
Click to expand...
How much better are those lights? I've been thinking of upgrading my 79, just havent decided what to go with.
 
I was reading other posts about it and wasn't convinced that it was worth the $$. I am now and would recommend it. Much better lighting than stock. Do it, you'll be happy with the results.
 
Cool, thanks. At this point I'm thinking anything would be an improvement on my 79...these things are so bad I'd be about as well off to hang my head out the window with one of those little headlamps on...although I might get more redneck style points for that!:o
 
So you just buy that upgraded harness and plug it right into the plug on the firewall and your done?
 
Nope, you gotta buy all the individual headlight, parklight and turn signal connectors, and some wire, and then "build" your own harness. If it's only your connectors that are the problem, you can just splice those into the existing harness. If not, you'll have to splice them into the wires that come out of the block on the firewall. I had some headlight flicker once, turned out to be bad connectors at the lamps, another time I had flicker on my Toyota, it was a bad fusible link at the battery. Hope this helps.
 
dasanii19 said:
So you just buy that upgraded harness and plug it right into the plug on the firewall and your done?
Click to expand...
Depends on the problem. As mofu already stated, you may have to rebuild the whole harness. The harness I referenced plugs into the passenger side headlight socket. If they are flickering, this upgrade will not fix it. The heavy duty headlight wiring harness only allows the addition of better headlights - sold seperately.

You have 6 sockets to replace, worse case scenerio, if you wanted to rewire the entire front lighting. It's not hard, just monotonous.

Don't buy cheap wiring and connectors. Here are a couple of online sources that others have recommended on this site:

http://www.electrofast.com/

http://waytekwire.com/
 
I would think by upgrading to the heavy duty wring harness would fix the flicker because it would be all new wring and new headlights? why wouldnt it fix the flicker?

So if I buy the heavy duty wriing harness it doesnt come with the right connectors I need? its just the wiring and relays? Meaning I will have to add the connectors I will need? Is that right?

And the heavy duty wiring harness does not plug into the original plug in on the firewall?

I just want to verify all of this because I am very interested in upgrading.
 
The heavy duty harness is designed to plug into an existing headlight socket. You unplug one headlight and plug it into the heavy duty harness.

Sockets.JPG

The headlight socket is wired through the new harness to two relays (1 - low beam and 1 - high beam). The relays take power directly from the battery to power higher powered headlights.

Relays.JPG

Your problem is somewhere between the firewall and headlight socket. If the existing harness is bad, the relays will power off and on because they are being activated by the original harness.

Sockets.JPG

Relays.JPG
 
Ok so what I should get is the new upgraded headlight harness, new high output headlights. Trace down my old headlight wiring to make sure there are no slices or anything abnormal in the wiring and replace all the connectors?

Is this a good start?
 
Yes, it is a good start. When you say you get flicker when you wiggle the wires, is it when you wiggle them at the firewall, or at the headlight connector? If the latter, then what you just posted would be a real good place to start. If you don't have one, get a proper crimping tool or solder the wires for a good connection, bad connections cause heat and subsequent insulation failure, and then you get corrosion.
 
Then thats what ill do. I have my whole front clip taken aprat on my truck right now so why the heck not upgrade my headlights at this point. Makes sense to me :D If im having any troubles ill post back up with questions, if not ill still post back up with the happy out come .. Thanks again!!
 
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