Universal wiring harnesses?

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Universal wiring harnesses?

Post by SonOfTheGrim on Sat Sep 26, 2015 3:47 am

I was wondering if anyone has used one of these universal wiring harnesses. Not necessarily the painless harness because $500 is a bit steep for my budget. The ones I am looking at are available on eBay and Amazon as well as a few other places:  click

What I am really wondering is how to determine the number of circuits versus the number of fuses I'll need for my car.


Last edited by SonOfTheGrim on Sat Oct 03, 2015 4:13 pm; edited 1 time in total
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Sun Sep 27, 2015 9:51 pm

Nobody knows?
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Re: Universal wiring harnesses?

Post by chevellelaguna on Mon Sep 28, 2015 8:25 am

The Painless ones are usually somewhat brand specific, very well labeled, and designed to mount in the same location with basically the same path for wiring your existing components. Quality wire harness.
The cheaper knock off ones... Well, particularly the one you listed, states it's a 20 fuse harness in the title. Under the description it says 15 fuse. If that isn't clear, how are the instructions going to be. Will the harmonica connector fit right up to your column, probably not, it's a vague universal kit. Specifically for a rod application. Have to find out where the fuse box is in relation to the wiring. Street rod harnesses typically mount the fuse box in the back of the car and run the wiring forward, mostly, except for the tail lights etc. is that how this one is, not sure. Things like that can pose problems. You'll be cutting and splicing a lot it wires to make that particular harness fit.
As far as circuits go, you can always add more circuits. Better to have more fused circuits. 15-20 for our cars is often sufficient for stock, are you running electric fans, fuel pump, stereo, HIDs, power windows. Stuff like that needs it's own fused circuit. That's 5-7 right there, all of a sudden the 15 one they list is already not large enough. You can always piggyback another small fuse box with 7-10 circuits to the base fuse box system.
It's your choice, just listing some areas to consider, mostly the length of the wires for a particular circuit.
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Wed Sep 30, 2015 10:57 pm

That clears up some of my questions. So it would seem that bigger is better just in case. I do plan some upgrades later on. Thanks for helping me out.
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Re: Universal wiring harnesses?

Post by pila on Wed Sep 30, 2015 11:49 pm

Is your original harness in really bad shape ? Putting a new harness in, even from Painful Wiring, is a project !

Helped a friend put one in a '69 Camaro.

Even installing an original that was removed for a body-off resto, is a project. Did that with my Elco....

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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Thu Oct 01, 2015 7:06 am

Yeah my wiring is pretty shoddy, especially under the dash. I have mystery wires running all over the place that I don't know. I actually think the brake lights are wired to a switch that is hanging down from the dash. Its that bad. I would take the harness from my camino but it is just as bad. I started looking into replacement harnesses for it. When I got the chevelle I was hoping the wiring would be in decent shape but I was very disappointed.

It just needs to be done, plus the idea of updated fuses and expansion for power windows, door locks, and seats is on my list.

Here is what it looks like under my dash.
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Re: Universal wiring harnesses?

Post by JKK on Thu Oct 01, 2015 10:59 am

actually i have used the "speedway motors 21 circuit" that cost far less than a painless harness, imho is a good quality harness, and all the connectors and terminals that comes with it works well. it comes with the gm steering column conector already , and have a nice brushed aluminum headlight switch.
it took me a little more than a weekend to install it as i want it.

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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Thu Oct 01, 2015 7:13 pm

That is exactly what I am looking for: A harness like that and someone who has actually used it.

Unfortunately it seems that Speedway has discontinued their line of harnesses so I can't buy one from them.
Fortunately it seems, from the pictures at least, that this is the exact harness that is available online like in the link above. I'll just have to be careful whom I purchase it from and make sure they give enough accurate information about it.
It may not be $500 but $150 is still a decent amount of change. To me at least.
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Re: Universal wiring harnesses?

Post by JKK on Thu Oct 01, 2015 9:42 pm

i buy 2 of them a month ago in speedway ebay store!

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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Fri Oct 02, 2015 1:52 am

Got a link to that? I can't find anything but Painless and American AutoWire on their site or ebay store.

There is this but it has been discontinued. Would have been perfect too...
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Re: Universal wiring harnesses?

Post by Joe73 on Fri Oct 02, 2015 12:06 pm

I've been looking at the this company for quite a while. They make exact factory reproductions. So they should be plug and play.

http://www.lectriclimited.com/mainpage.htm
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Re: Universal wiring harnesses?

Post by JKK on Fri Oct 02, 2015 2:24 pm


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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Sat Oct 03, 2015 3:18 pm

Joe, that company looks like the place to go BUT if I had to guess I'd say you'd end up spending more than a Painless harness. Just an assumption.

That 12 circuit harness looks great but would that be enough for our cars? I know if I ever get around to putting in power windows it won't be.

That EZ harness seems like the one that most everyone carries now. I've read some good and some bad things about them, like you get what you pay for. But I am prepared to have to do some work on any "universal" harness I decide on. You know what they say: Universal fit means universally doesn't fit anything, right?
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Sat Oct 03, 2015 3:21 pm

Actually this looks like a much cleaner harness than the EZ one. Maybe I'll go with this one if I can find some reviews about it.

And I actually contacted the seller of the harness I linked to first and he got back to me very promptly and confirmed that it was a 20 fuse harness, not a 15. Its the same as this^ one.
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Re: Universal wiring harnesses?

Post by thatfnthing on Tue Oct 06, 2015 10:40 am

SonOfTheGrim wrote:You know what they say: Universal fit means universally doesn't fit anything, right?

Absolutely right. My other concerns would be that for that price they don't supply enough wire length, and/or worse, the wire gauges are too small for heavy-draw circuits like power windows. Any way you slice it, you will be doing extra fabricating like lengthening wires and finding a new way to mount the fuse box, which will not mount the same way your old one does, even with a Painless harness. So in turn you will also have to come up with a new way to secure the firewall bulkhead connector, which is held in place by the stock fuse box. The point is, you can make anything work, but it will be a bigger job than anyone tells you, even the Painless people, because there will be mods you'll need to make for your particular car, especially if you go off script and add a bunch of extra features your car didn't come with.

My other suggestions would be:

1) Get as many circuits as possible to start -- easier to not use them now and have them available for later than to try to add them in afterward.

2) Use self-resetting breakers (not fuses) for high-draw things like power windows, seats, locks, etc.

3) Make sure you have some other automotive electrical experience. This is a big job, and it will be a lot easier if you've already got some other electrical projects under your belt.

FWIW, another route is to use an existing harness from another car. I used the harness from a 93 Caprice wagon and it worked out great, but I had a lot of extra work to do to relocate the fuse panel, track down appropriate connectors & terminals, etc. However, it gave me the ability to add things like ABS, daytime running lights, power mirrors, etc. I could even add in airbags later if I feel the need for a challenge. Smile

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Re: Universal wiring harnesses?

Post by Hawk03 on Tue Oct 06, 2015 11:26 am

I should probably add more circuits but I don't want to rewire the whole car.

How would you add more circuits to the stock setup? Do you add an additional board and run a wire from the alternator/battery? Or would you piggy back off of the stock board some how to make sure it only runs when the car is on?
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Re: Universal wiring harnesses?

Post by thatfnthing on Tue Oct 06, 2015 12:46 pm

The first thing to consider when adding something electrical is the expected current draw of the thing you're trying to add.  Your primary options would be:

1. Tap into an existing circuit.  You could get away with this if you are adding something with a very small current draw.  For example, you could simply splice an LED into the instrument panel lamp circuit, especially if you've lowered the normal current drain by switching all the other lamps on the circuit to LEDs.  In this case, you've drastically lowered the possible maximum amount of juice, so there's capacity to spare.

2. Add a new circuit. This will involve exactly what you describe above -- a new feed from the batt/alternator (or ignition switch or existing fuse block) running to an inline fuse or a mini-fuse block.

The next thing to consider is when the thing needs to have power.  If the answer is 'always' (i.e. even with the ignition off), you can run straight from the batt/alternator to the fuse, and then to the device.  If the answer is 'only in run' or 'only in accessory', then you are looking at splicing directly from the appropriate feeds from the ignition switch, then to the fuse, then to the device.

Last thing then is wire gauge.  This will be determined by the total amount of current the circuit is expected to carry for any length of time.  Too small a wire gauge, and the wires will run too hot and introduce too much resistance, which will play hell with electronic devices and sensors.  I tend to go more conservative than the factory, so I use roughly this scale:

1A or less = 20ga
1A to 5A = 18ga
5A to 10A = 16ga
10A to 15A = 14ga
15A to 20A = 12ga
20A to 30A = 10ga

Also be aware that the ground wire will need to be the same gauge as the feed.

And a word of caution: Under no circumstances should anyone just add stuff to an existing factory circuit and put in a larger fuse.  While the fuse will allow the larger amount of current through, the wires were sized according to the original expected load.  Pulling more juice through a wire that's too small will create heat.  LOTS of heat.  Possibly even enough to melt the insulation or wiring, or even start a fire depending on how much current you're trying to stuff through them.
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Thu Oct 15, 2015 9:15 pm

I am very interested in this idea; using a newer harness from a different car. I would love to know more about how you did it.
I got under the dash today to figure out why my freshly installed motor won't crank and found that my harness is completely screwed. It is so cut up and sliced I don't think it's even safe to use.

Do you have any pictures or a thread about using the caprice harness?
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Thu Oct 15, 2015 9:45 pm

Looking around on eBay I found this.

Does that look like an EZ harness to anyone else?
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Re: Universal wiring harnesses?

Post by thatfnthing on Fri Oct 16, 2015 10:58 am

SonOfTheGrim wrote:I am very interested in this idea; using a newer harness from a different car. I would love to know more about how you did it.
I got under the dash today to figure out why my freshly installed motor won't crank and found that my harness is completely screwed. It is so cut up and sliced I don't think it's even safe to use.

Do you have any pictures or a thread about using the caprice harness?  

Other than that shot of the fuse panel, I didn't really take any photos.  The fuse panel was the most interesting thing visually -- I figured, who wants to look at pictures of wires? Smile

In addition to the 93 Caprice harness, there's also a fair portion of 86 Camaro for the TPI grafted in, as well as a LOT of custom stuff (Vintage Air, overhead console, keyless entry, power windows/locks, lighting subpanel, etc).  Basically I went so far off script that I didn't think a thread would be as helpful as just assisting where possible on people's individual issues/projects/ideas.

So if you want pictures/diagrams of something specific I did (or you want to do), I am happy to provide on an as-needed basis. Smile


SonOfTheGrim wrote:Looking around on eBay I found this.

Does that look like an EZ harness to anyone else?

I wouldn't start with that one.

What are your goals?  Are you looking to just replace your worn harness with something more reliable, or are you looking to do a lot of custom mods down the road?  If the latter, what kind of features were you looking to add in?

If all you want to do is make the car work again, I'd probably go with a prebuilt harness like Painless or equivalent.  It will still require a fair amount of work, but not as much as grafting in the harness from another car.  It's designed to handle the usual stuff your car might need.

On the other hand, if you're planning to go hog wild with mods like I did, then it makes more sense to start with a 91-96 Caprice/Roadmaster (or other GM full size vehicle from about that period) harness -- these are very similar to our cars, have a lot of interesting factory features, and -- most importantly -- are much easier to modify than a prebuilt harness.  But make no mistake, they're more work, and you will need the factory service manual for the donor vehicle in order to understand what goes where.  However, you will gain huge insight into how things work, and therefore be able to do things no prebuilt harness will handle.

So the question is -- what's the plan?
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Fri Oct 16, 2015 4:13 pm

My goal for the wiring is to update it to modern fuses and get away from those glass ones (of which I broke 2 last night because the ends were rusty and stuck), and to get rid of every single cut and splice and hack done by previous owners. I'm not going for stock but simple and reliable. I want good clean wire, good clean connectors, and good clean routing. As far as future projects and additions, I want to eventually do power windows and locks and I have a (driver) electric seat I will be installing. I really don't want anything crazy. Maybe a good stereo, but not like subwoofers and amps. Just a good set of 4 speakers and head unit.
The thing that draws me to the unliversal harnesses is the modern fuses and new box clearly labeled as well as the actual wires being labeled every few feet. Why doesn't every car manufacturer do this?

I know that harness from the truck wasn't a good starting place, I just thought it was funny. But considering using a harness out of a different car has got me curious. What were your criteria for looking for a harness? What things did you look for in the car you were taking from?
I think my biggest thing to consider is the fact that both of my cars have HEI electronic ignition from the factory. This has been the biggest challenge when looking for wiring diagrams and such because the diagrams all have the old coil style, even for a 76 or 77.

So if I were to look for a harness from, say, a 78+ chevy truck how far off would it be layout and color wise? I think anything after about 1976 would have HEI and be less of a modification.

Here is what I am dealing with under my dash. Someone invested in a spool of yellow wire which they used for EVERYTHING, there are random bad splices to and from everything, things taped up and hanging down. You name it, its under there.


I also think my ignition switch might be bad because I get power to the switch but not to the starter soleniod. That was my dad's diagnosis tho. He's the electrician.
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Re: Universal wiring harnesses?

Post by thatfnthing on Fri Oct 16, 2015 5:53 pm

SonOfTheGrim wrote:My goal for the wiring is to update it to modern fuses and get away from those glass ones (of which I broke 2 last night because the ends were rusty and stuck), and to get rid of every single cut and splice and hack done by previous owners. I'm not going for stock but simple and reliable. I want good clean wire, good clean connectors, and good clean routing. As far as future projects and additions, I want to eventually do power windows and locks and I have a (driver) electric seat I will be installing. I really don't want anything crazy. Maybe a good stereo, but not like subwoofers and amps. Just a good set of 4 speakers and head unit.
The thing that draws me to the unliversal harnesses is the modern fuses and new box clearly labeled as well as the actual wires being labeled every few feet. Why doesn't every car manufacturer do this?

I hated my barrel fuses too for the same reasons, which was also a motivator for me (along with other things, more on that below).  It sounds to me like a prebuilt harness will suit you pretty well then.  Get one with 20 or more circuits, and it should include things like breakers for power seats, windows, etc -- like I mentioned earlier, it's better to get those additional circuits now than to to try to add them in later.  There will still be some work involved, but the fuse panel end will already be done.  Your concerns will be where/how to mount it, how much of the old harness to keep and where to splice, and tracking down vehicle-specific connectors and such that the universal harness won't come with.  

SonOfTheGrim wrote:I know that harness from the truck wasn't a good starting place, I just thought it was funny. But considering using a harness out of a different car has got me curious. What were your criteria for looking for a harness? What things did you look for in the car you were taking from?
I came at it from a different direction, really.  I didn't go looking to replace the entire harness from the outset.  I actually started with the TPI, which needed its harness almost completely rebuilt, and it taught me a LOT.  Then I was determined to retrofit ABS after I learned how similar the 91-96 Caprice cars were to ours, and that the ABS system was standalone.  From there, then, it was a short leap to grafting in the rest of the harness from the Caprice, since there were a lot more things I wanted to add, and the stock harness would simply never support it, even if it had been in good shape.

SonOfTheGrim wrote:I think my biggest thing to consider is the fact that both of my cars have HEI electronic ignition from the factory. This has been the biggest challenge when looking for wiring diagrams and such because the diagrams all have the old coil style, even for a 76 or 77.
Actually, HEI is the least of your worries.  It's incredibly simple -- one 16ga feed wire that's hot in Start and Run.  That's it.  Just one of the many reasons people upgrade to HEI if they don't already have it.  The universal harness is even likely to have a circuit for that already (if it contains an engine harness).  Though it does surprise me that you're seeing post-74 wiring diagrams with points/coil -- my understanding is that all GM vehicles from 75 and up had HEI, so you'd think they would have updated the diagrams.

SonOfTheGrim wrote:So if I were to look for a harness from, say, a 78+ chevy truck how far off would it be layout and color wise? I think anything after about 1976 would have HEI and be less of a modification.
GM has been very consistent with their wiring for decades across all their models -- same colors, gauges, and circuit numbers.  Even the striping.  They simply added more as they needed them.  For example, many of the circuits in the stock G3 harness are the exact same color, number, and gauge as in the 86 Camaro and 93 Caprice I used, and also an early aught-something Grand Am harness I bought just to have extra lengths of wire.  So in theory, any GM vehicle could provide a donor harness.  I'd look for condition, wire length (a Chevette harness would likely be too small), design of the fuse panel, number of factory features, and availability of the factory service manual (which will be critical).

SonOfTheGrim wrote:Here is what I am dealing with under my dash. Someone invested in a spool of yellow wire which they used for EVERYTHING, there are random bad splices to and from everything, things taped up and hanging down. You name it, its under there.
Yeah, all the same color is the first thing you DON'T do.  You could repair it by tracing each of the 'fixes' and replacing it with the proper color and gauge of wire, but you're right -- this is an optimal time to upgrade the whole thing.

SonOfTheGrim wrote:I also think my ignition switch might be bad because I get power to the switch but not to the starter soleniod. That was my dad's diagnosis tho. He's the electrician.
That's possible, but there could be other causes, too.  I'll go back and look at the diagrams we have posted in the sticky for the electrical section and see where else you might look.
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Tue Oct 20, 2015 3:36 am

Well I haven't found a harness yet or decided to buy a new one. But in the meantime I am working through the mystery of my harness and trying to figure out what the PO was thinking and what some of the additions and subtractions are. I have some pictures if anyone can shed some light for me.

First here is my engine harness from the junction block at the firewall. As I understand it the 73-75 models use a pink wire going to the coil and a purple wire going to the starter solenoid. Well my 77 has a tan wire going to the HEI and a pink wire going to the starter sol (this is how the harness was set up but I wonder if the PO wired these backwards).
I am also confused about the fusible link coming from the hot wire terminal because why do you need a fusible link if you have a fuse in the fuse box???


Next is back to under the dash. This silver cylinder next to my fuse panel, it just has the blue connector plugged into BAT and the blue connector at the bottom of the screen has a yellow wire plugged into it but it is cut about a foot down and goes nowhere.


My neutral safety switch on the column has the green and pink connector plugged in but I can see another place for a double connector but nothing that looks like it plugs into it. I *think* it is supposed to have purple wires plugged into it?


This. What the hell is this?


This is the last question for now. I am sure everyone is getting tired of my goings on. I can't seem to find anything on any wiring diagram with a gray, black, and yellow connector.



Again I thank everyone for the information. You people are incredible. By the time I get through this puzzle of a car I'll probably be an expert at wiring and a whole lot more.
Hopefully these questions will keep me busy for a while. I am at this point just trying to get the damn thing to crank.
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Re: Universal wiring harnesses?

Post by SonOfTheGrim on Tue Oct 20, 2015 5:29 am

I have also concluded that my entire dash is going to come out and be repaired/strengthened as it is loose and wobbly and not properly fastened at all.
Another endeavor, maybe for when I get my new harness.
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