Wiring harness 101

Uncle Skip · Post by **Uncle Skip** » December 1, 2008, 7:06 pm

Part 1

Since we're going to wire, or re-wire our trucks, this is the first installment in "Slick wiring for the Complete Idiot".
I know there are experts out there that know everything there is about electricity and wiring, and this is probably child's play for them, but my problem is I can never find a child for a job like this when I need one, so the "idiot" I refer to is me.
I am the idiot because I could NOT under any circumstances, seem to understand those wiring schematics and make any sense from them.
I need to see stuff work before I get it. I'm now going to try to make it easier for the rest of us to get it right.
First, if you're going to understand how your truck is really wired you need to take your wiring harness out of the truck and make one of these test boards.
WHY? These things areover 40 years old and the wires, connections, switches and everything else including PO's splicing with electrical tape can be, and probably are, crap.
Also, the colors on the wires have probably faded to the point where you can't recognize them..... or, you're color blind in the base case like me.
Look close and you'll see just how simple this is.
For a power source, I used a motorcycle battery but you can use almost any 12 volt source.
The rest of the stuff is things you already have laying around your shop.
You need some scrap wire, some counter sunk machine screws that are put in from the bottom, a couple of fender style washers, a cheap trailer side marker light (or anything else you have laying around) and some Radio Shack probes or alligator clips. I like the clips.
Also, the deck screws hold the clips when you're not using them and keep them from accidentally getting together and shorting out the system.
The last photo shows how I hooked up the board to the new (old) Ron Francis fuse block I got at Pate last year.
Here are the photos of the test board.

TO BE CONTINUED......................................
Uncle Skip

cookster4495 · Post by **cookster4495** » December 2, 2008, 8:44 am

NICE,, I Likeeeey

36truck · Post by **36truck** » December 2, 2008, 9:42 am

This is going to be good. Great work Uncle Skip.

don morris II · Post by **don morris II** » December 2, 2008, 11:02 am

i know this will help me a lot thank you

ICEMAN6166 · Post by **ICEMAN6166** » December 2, 2008, 11:34 am

that is very nice.

Uncle Skip · Post by **Uncle Skip** » December 2, 2008, 8:47 pm

Part 2

If we’re going to do this re-wire project, I suggest you get yourself a good and inexpensive wiring harness. I can recommend several good suppliers that are less expensive than Ron Francis and probably just as good. Ron is excellent and has a very good reputation for quality, but we're building trucks, not mega-dollar street rods, right?
Why?
Duh, do you want to burn your truck to the ground?
The old harness has very few fuses and what is there is in the light switch or in a little dinky under dash fuse block.
The reason to re-wire is, after 40 + years, things like wire and connectors start to get brittle, insulation cracks and wires become corroded and generally un-useable.
I've checked several old harnesses (on my test bench) and when I found a dead wire, it almost always had cracked insulation: in each case, I stripped it back to look at the wire and it was corroded badly.
So, lets do it once, and do it right.
Guys, I strongly recommend that you remove the harness from your truck before you start this project. It’s pretty easy considering all the other stuff you’re going to do, or have done already. And wiring is one of the second most important systems on your truck behind brakes.
Then test it with your Handy-Dandy-Little Dude test board you just made.
During all this, I realize that my written instructions aren’t always the best way to communicate an idea, so when I talk about something confusing, I’ll post pictures so you can see what I’m talking about.
Hell, what am I talking about, everything with wiring is confusing……

Your moments of Zen.
First, you need to decide if you’re going back with all stock switches, semi-stock - original switches with some toggles, or full boogie toggle replacements.
Remember, if you choose new toggles, you’re going to need a switch for every function if you go with toggles, or a combination thereof.
If you’re going back bone stock, you need to clean and rewire every switch you have. Also, e-mail me and we can talk about how to clean up the switch and wires.
So grab an adult beverage and a pad and pen and go sit in the truck and think about “stuff”.
Draw pictures, make notes. It makes you feel better and keeps you from chopping stuff up and then finding out you didn’t have enough room a long enough new wire, or maybe didn’t allow for something you forgot.
All these little drawings and notes help remind you where you were going with your ideas.
YOU NEED TO DO THIS ROUTINE SEVERAL TIMES. Trust me.
Think it thru.
If you splice in the old switches, its pretty much a no brainer except for cleanup and splicing in new wires.
If you’re upgrading, you can put everything on toggle’s. (That is unless you have a 2-speed delayed wiper switch. In that case, you’ll have to use the switch that came with the delayed wiper.)
If you don’t have a delayed wiper, you can use a double pole double throw [center off, up on, down on] for low and high speed.
[actually, we can toggle the delayed wipers too, but it's a little more involved than I'd like to get into here].
Make your list of what you're planning, include what your objective is going to be, and get back to me if you have questions.
Next time we'll talk about switches, wires, and system amperage loads.
Am I making sense here?
To be continued………………
Part 3 is coming.
U@ss

Uncle Skip · Post by **Uncle Skip** » December 2, 2008, 9:20 pm

Part 3

Understanding wiring amperage loads.
I respectfully direct you to a previous post in the hints and tricks forum, explaining the load capacities of different wire gauges.
This is relative when you select your switches.
Copy it for your 3-ring binder and refer to it often.
http://www.fordtruk.com/forums/viewtopic.php?t=6991
To be continued............
U@ss

Uncle Skip · Post by **Uncle Skip** » December 13, 2008, 9:07 pm

Part 4 - kind of.
The holidays have slowed progress on this project. Its been cold, wet, and busy so I didn't want anyone to lose interest.
(I hope this submission makes a little sense to you because I don't have pictures yet.)
So, start amassing parts for the job we're going to do.
Your local wrecking yard is the place to start.
We need to start getting matching male and female plugs so take your side cutters and go to the yard and start searching for (GM) multi-wire plugs that have a male and female side.
Cut the plugs with as much extra wire as you can so you have enough pigtail to splice to.
For you Ford diehards. Don't panic about using GM stuff.
There is a valid reason for this GM selection. We can buy new internal connectors for these plugs. You remove the old wires with a very tiny flat screwdriver by pushing the little retaining clips up and pulling the old wire out. Once the new wire is attached to the new male/ female connector and pushed into the old plug, you have a new custom plug.
Get as many different plugs as you can find and make sure they're using at least 16 gauge wire.
Two wire plugs, 6 and 8 wire plugs, and maybe a big multi-gang plug or two.
The plug I'm using for my instrument panel is out of a mid 90's Caddy and is an 8 pin plug.
I have a universal ground, the high beam, left and right turn signals, instrument lights, fuel sender hookup, and voltmeter hookup, so I've pretty much used up all the available plugs.
Its going to be the same thing for the steering column turn signals.
That 6 pin plug will include power in from the flasher, left and right - front and rear each, turn siganl out, and the horn ground wire.
I'll be posting more pictures as we go on so maybe I can add something to make sure you can understand what I'm talking about.
Trust me, just go plug hunting.
I WILL take some pictures so this mishmash will make some sense.
Stay tuned, film at 11:00.
U@ss

Uncle Skip · Post by **Uncle Skip** » December 14, 2008, 10:01 pm

Don't pay a big price for wires or connectors if you don't have to.
There is a very important un-used resource we all go to but don't think about taking advantage of.
Your local junk yard. I got all this stuff except the plug from said junk yard. Yeah me.
Pay attention to the first picture.
I got this plug kit from a wiring harness vendor, but its typical for most cars and the little prongs on the metal connectors show what you have to compress to take the prong and attached wire out of the plastic plug.
The male plug retainers compress from the side, the females compress from the little tang on the top.
The other pictures show what I was able to get from my local wrecking yard for about $10.00, including relays, plugs, fuse holders and such.
Some of the wire rolls are almost 12 feet, one piece. Some from a mid 90's Lincoln Town Car, the other stuff is from a Cadiallac.
I think new relays are about 15.00 each without a connector.
I also got some toggle switches I forgot to take a picture of.
Cheap stuff for a rewire project.
(I have some more long lengths of wire coming from Leonard in Colorado via a special deal he got, but that is a special story for a later time.)
Stay tuned.
U@ss

DCarr · Post by **DCarr** » December 14, 2008, 10:27 pm

Thanks, Skip. There's also a weatherpac tool available to compress the little prongs in the plugs so you don't have to pry with a screwdriver.

Uncle Skip · Post by **Uncle Skip** » December 14, 2008, 10:35 pm

DCarr.
Thanks for the info.
Please post the tool name or number and where you can buy it.
It has to be better than prying around with one of those jewelers scredrivers.
U@ss

DCarr · Post by **DCarr** » December 14, 2008, 11:00 pm

Skip, the tool I have is a Snap-on GA500A Wire terminal tool. It has 6 sides for terminals with different sizes/shapes of connectors. Snappy also has several other models of terminal tools and soft grip terminal tools for the different size pins on late model wiring harnesses. Other tool trucks may have similar tools.

Uncle Skip · Post by **Uncle Skip** » December 15, 2008, 9:42 pm

Paid another $2.00 today for 6 more connectors.
I just noticed something today too. Seems like FoMoCo uses bullet style connectors, and GM uses blade type connectors. I never saw that before.
One of the better ones I got is the newer type sealed 6 wire plug that will go in the back of the truck to connect the rear lights.
2-turn signals
1-brake light, both sides
1-tail light light, both sides and license plate light
1-backup light
1-extra for something unique

Now I can unplug one plug and pull the bed.
A couple of the others I got are relays with plugs and some heavy duty plugs for ignition and fuel pump wires.
Remember, if you're buying plugs, get the male and female sides.
To be continued.........

Uncle Skip · Post by **Uncle Skip** » December 16, 2008, 8:13 pm

FYI.
I found a really nice Autometer 3" tach today.
$1.00 and it works perfectly.
I love the junk yard.
U@ss

36truck · Post by **36truck** » December 16, 2008, 8:23 pm

I only wish I had a junkyard here that was as good as yours Skip.

Uncle Skip · Post by **Uncle Skip** » December 16, 2008, 9:04 pm

Tom.
There is a really nice little fat girl with missing teeth that controls what goes in and what goes out.
She was going to give me the tach, but I wanted to give her something in return.
So a cold Dr Pepper seemed like the thing to do.
If you talk nice to people like that, get to know them, buy them a soda or something like that without their asking, and they appreciate you, and they never forget what little kindness's you've given them.
Charlotte loves Oreo's. So guess what I bring to the yard when I go.
Be smarter than your adversary.
Spread the joy.
U@ss

Alan Mclennan · Post by **Alan Mclennan** » December 16, 2008, 9:11 pm

They have to put up with some real dopes!

36truck · Post by **36truck** » December 16, 2008, 9:11 pm

That doesn't help when you know all the guys that work at the yard. Just no deals there.

Uncle Skip · Post by **Uncle Skip** » December 17, 2008, 8:04 pm

After reading some of the other posts, it occurs to me that I've neglected to list the neat stuff you can find at your local wrecking yard for our re-wire project.
Basic wire. Some of the bigger cars have miles of different gauge wire. Pick and choose your gauge and get the longest lengths you can.
Inline fuses for the radio.
Inline blade type fuses for almost anything. These puppies have a sealer top and you should cut the wires as long as possible.
All manner of connectors and plugs. Again, take as much wire as you can.
That heavy duty red copper wire that is used for as power supply for the big ground pounder amps is great for ground wires. And usually there is some type of multigang splitter connector for power from the battery.
Mustangs have a neat little round splitter post for connecting multiple hot wires and it has a cover to keep you from accidentally shorting it out.
I found some toggle switches, some rocker switches, and neat little slide switches I have no idea what I'll use on. Did I say they were neat?
Also, even though the new stuff is cheap, you can get miles of the corrigated plastic wire cover with the splitters and end connectors for almost nothing.
Seems like all then new cars use this stuff and it makes a neat installation.
Just be sure to take a razor blade or sharp knife to cut the electrical tape, and a pair of good side cutters next time you go and stock up on cheap parts.
After Jan. 1, I'll submit my idea of a wire loom for pre-routing our wires from the fuse block (or what ever) to the switches, firewall plugs, and to the systems. Might work, might not. But when I do, I'll post pictures and see what you all think.
U@ss

Uncle Skip · Post by **Uncle Skip** » January 21, 2009, 7:24 pm

Looks like I'm finally ready to start prepping for the re-wire.
I got a message from Leonard about measuring for the wires for his new switch panel.
So at this point I need to caution everyone to be careful not to wire in a straight line without leaving a "service loop" under the dash.
That is, go ahead and bundle the wires but be sure to leave several inches of slack in the bundle so you can pull things out and still have room to work on any future problem that might pop up.
Also, in case you can't find enough different colored wire to have a unique color for each circuit, find some method to mark each wire on either end so you can avoid having to guess what goes where when you have to pull something like a switch off to replace it.
I'm going to use numbers from 1 to 33 to match the terminals in my fuse block. I'll tape a small ring around the wire near each terminal with masking tape and number it with a Sharpie.
Also, to avoid confusion, ALL my ground wires, and ONLY my ground wires will be black.
I'd record all that stuff in my three ring binder. Numbers work fine as long as you record the information.
When I finish my mock up board and start running wire, I'll post pictures of what I'm talking about.
I'm also considering using solid red only for primary power supply wires, but we'll see about that when I get started.
More later.
U@ss