making wiring harness from scratch

-
blue missile

blue missile

Well-Known Member
Joined
Oct 20, 2008
Messages
2,151
Reaction score
78
Location
Austin Texas
OK,
Its starting to get cool here in Austin, so Im lining up inside tasks for the build. One of those is to build a wiring harness from scratch. I have the wire in a 15' piece of elevator traveler cable.The cable has about 50 pieces of 20ga wire all with a different color code and striping.
What I need is a source for the bits to make the connectors to say the lights, and other factory connector ends.
Andrew
 
I am just posting so I remember to re visit the thread, when I remember who sells the pigtails, and connectors.

One of the places that repops the harnesses will sell the fire wall plugs, but you have to ask nicely in private.

Many of the plugs can be harvested at junk yards off of 80's trucks. If you want to go used.


Building a harness is not hard once you get the hang of getting the connections in and out of the plugs!
 
I used to build wiring harnesses in the Navy for weapons systems. The easiest way to get it right it was to lay out an example harness on a sheet of plywood, use larger nails to hold the harness in position on the out sides of the harness run like a guide of sorts. draw out the individual wires where they branch off and label them on the wood. Use a finishing nail to mark where the harness wire terminates. Then after removing the example harness its a simple matter of running or laying the wires of the proper color coding and take a couple turns on the nail where the wire should terminate. There are probably simpler ways of doing it but this was a sure fire way of getting it right every time.

Of course this could be used over and over so if you decide to hook us up and produce some extras you would be set up to do that!
 
i think year one sells the firewall plugs....if the bulkhead connectors themselves are still good, you can get the terminals from here...http://www.wranglernw.com/
download the catalog and go to page 48. for 16-14 gauge wire the numbers are male p/n 32-737f and female p/n 32-737f. they have them in 2 different sizes also. if you hunt around you can find pretty much al of the pigtails to make your own harness. i will need to do this for my own car, i have all the sources written down somewhere, when i get back from the doctors i will post it all if i can find it....
 
inkjunkie,
great resource, they will hear from me.
I will be getting a sheet of 1/4" ply and laying out a full size firewall back on one side and firewall forward on the other. There will be a number of relay locations so there will be sub assemblies.
I will not be using used gear for this, right now what I lack is a source for a reasonably priced multi-pin bulkhead connector .
I will of course take pics.
I just picked up the two pieces of cable, one has 25/10ga conductors and the other has 50/14ga conductors.
I still have to draw up the complete schematic, but thats what the winter's for.
Andrew
 
Contact Bill Evans, he sells harnesses and has a good selection of the connectors available at the shows. Not sure if he has the bulkhead connectors, but it doesn't hurt to ask! I've bought from him, and he is a nice guy - and very knowledgable about Mopar wiring!

http://evanswiring.tripod.com/
 
I'll tell you how I've done it on about 4 cars and trucks with which I have had excellent results. This method is especially recommended for the guy who has more time than money, and wants to wind up with an improved harness to boot.

Remove the old harness and lay it out flat. Then run new wires alongside it to determine the correct lengths for each wire and cut them to length. It is nice if you can use the same color wire in each position as the original harness had, but you might have to buy a lot of wire that way. Using old, leftover wire hanks is OK, even if the insulation is the wrong color, but maybe you'll want to label the wires if you do that because the colors won't correspond to the schematic.

I think it is important to use a larger wire gauge than was used originally because none of the Detroit auto manufacturers designed enough headroom into their harnesses to prevent voltage drop due to degradation of the wire after a period of years. They chose the smallest gauge wire possible because copper is expensive.

I use one gauge larger for most wires, but for the combined battery/starter/alternator (main power feed) wire, I use two gauges larger. (If the two-gauge-larger wire is really stiff, I'll wind a pigtail spiral into it before connecting it to the alternator, in order to absorb engine vibration.)

I cut off all the old wires maybe an inch or two from the connectors. Then I clean the old connectors up carefully until all the pins are shiny (and the same for the connector it mates with).

Then I strip the old wires at the connectors maybe 1/4" to 1/2" or so, and the same for the replacement wires. Then I tin both stripped ends thoroughly with rosin core (not acid core) solder, so you've got about as much solder as the wire will hold on the tinned end before it drips off. Tin both the wire protruding from the connector and the new wire that you want to connect. Then hold the two tinned portions of wire together, parallel to each other, and hit them with the soldering iron until the solder flows cleanly around both wires. Don't twist the wires at all. You don't need to; it is more work; it makes the harness bulge too much; and it actually weakens the connection mechanically because the method I'm describing makes a very strong joint due to a large soldered contact area.

You will be replacing the soldering lugs, even though you use the old connectors over again. For the large wires, don't use the light-duty soldering lugs that are intended for electronics use. Go to the auto parts store and buy some more brawny lugs than the electronics type.

After you're done soldering all the new wires onto the old connectors and wrapping them with insulating tape where soldered, wrap the harness in a spiral fashion with fiberglass heat-resistant tape (the kind that people put on their headers to keep it cool under the hood).

On some cars you have to remove the intake plenum or manifold in order to replace the main engine harness. That is a drag, but it gives you a chance to clean the engine block, etc. up nicely.

This kind of a rebuilt harness is really bulletproof, even if I do say so myself, and the use of larger wires will improve the performance of your electrical system.
 
a while back i swapped a fuel injected 4.0 Ford motor into a Ranger that did not have efi. Really was not all that tough, just started at the computer, numbered each wire and did not terminate everything until i had everything in there. took several days, but i was working 10 hours a day at the time. when i get my car together i will have to wire it. mice had a field day, and with all the added electronics, efi, trans controller, fuel pump controller, head lamp relays etc it just does not make much sense to just try to use a factory style harness. i have not found my notes as to part numbers for pig tails etc, but i am looking.....
 
tyler_s18 said:
this will be cool to see. i personaly think it would be easier and worth it to get the ez wiring universal kit. it was like $150 with wiring and its all labeled. for me that would be plenty big enough project lol

http://www.ezwiring.com/wiring_harness.html
Click to expand...

problem with a kit, at least for me, is there is either to much or to little, whether it be wire length or circuits. was helping a friend who had a wiring kit, a couple of wires were to short and we could not find the same color wire, nothing looks worse then seeing a yellow/red trace wire turn into a plain red......not to mention the associated splice and shrink tubing sticking out screaming LOOK AT THE IDIOT THAT DID THIS!!!!:toothy10::toothy10::toothy10:
 
Guys thaks for the feedback,
I was incorrect in the original assessment of the wire gauges. They are 18 &14ga I will be getting some 10ga for certain runs.
Because this is elevator traveler cable there are about ten different colors combined in the two spools.
The reason I went chasing this stuff is that every piece of wire is individually numbered along its entire length. So Im not at all concerned about matching color codes to the existing harness.
When this is done I will have a spread sheet with all the numbering and terminations, and a complete CAD schematic for the car. I already have some of the engine compartment's added wiring done as far as the safety, security and oiling interlock system.
This is also the time I have to decide where all the stuff in the trunk will be located for wiring purposes. As one person wrote this is where i have more time than money so no rush here.
Andrew
 
Checking in on this thread.
A few questions as well:
What gauge wire is a typical a-body wiring harness?
Is it all the same gauge? (dash, under hood, etc)
What gauge is the starter, battery, alternator wires?

Just want to make sure if I am going to go up a gauge that I know where I am starting.

I think the bulkhead connectors are the same as the other connectors throughout the car, is this correct?
Also, I have seen the connectors on e-Bay.

I am thinking it might be best to replace the colored wires with the same color, but I have had zero success finding the correct colors wire. Any one have any suggestions?

Sorry for all the questions, but my wiring has been butchered and I am in the process of correcting it all.
 
One thing that concerns me about the elevator cable is its heat resistance. Should be fine from the firewall back, but you might want to use high temperature wiring like TXL or GXL under the hood. There's quite a big difference in how the insulation holds up to high temperatures between different grades of wire.

matthon said:
Checking in on this thread.
A few questions as well:
What gauge wire is a typical a-body wiring harness?
Is it all the same gauge? (dash, under hood, etc)
What gauge is the starter, battery, alternator wires?
Click to expand...

There's a lot of different gauge wires - your best bet is to get a factory wiring diagram, which will have them all listed.

I think the bulkhead connectors are the same as the other connectors throughout the car, is this correct?
Also, I have seen the connectors on e-Bay.
Click to expand...

The bulkhead connector is its own animal - it's probably in the same series, but it's not the same connector itself. If correctness is not an issue, I'd be tempted to eliminate the factory bulkhead connector, and either use a more modern design or just run the wires through a firewall grommet like modern cars do. They're one more thing to break.

I am thinking it might be best to replace the colored wires with the same color, but I have had zero success finding the correct colors wire. Any one have any suggestions?
Click to expand...

If you're not sure what color you should be using, again, you'll want the factory service manual diagrams.

If you're not able to find the right wires, you might want to try Waytek Wire - they have quite a selection, and in the right grades. We've got a lot of their spools hanging on the wall where I work. Biggest problem is it can get expensive to build a single harness, which is why some of those prepackaged kits can be quite helpful.
 
May I ask why you are doing this. I have bought both the engine forward and under dash wiring harnesses from year-one. I paid 150.00 for the engine forward and 500.00 for the under dash. The second seems to be costly but I would say well worth it. Both come with all new wiring and factory correct connectors. The under dash comes with a brand new fusebox and firewall connection block. =P~

On the other hand I believe 20 guage wire may be too small. Most of my harnesses use 18, 16 and 14 guage plus some larger ones for the main feed to the amp meter from the engine compartment. 8)
 
The factory wiring diagram I have does not list the wire gauge, doh!
I was successful in getting a cherry dash harness, I just need to fill in the blanks on some other wiring.
 
inkjunkie said:
a while back i swapped a fuel injected 4.0 Ford motor into a Ranger that did not have efi. Really was not all that tough, just started at the computer, numbered each wire and did not terminate everything until i had everything in there. took several days, but i was working 10 hours a day at the time. when i get my car together i will have to wire it. mice had a field day, and with all the added electronics, efi, trans controller, fuel pump controller, head lamp relays etc it just does not make much sense to just try to use a factory style harness. i have not found my notes as to part numbers for pig tails etc, but i am looking.....
Click to expand...
sorry i dropped the ball on this. i have torn my garage apart looking for my notes and can't find them. i had a carquest book that had pretty much all the plugs, pigtails etc in it that are needed and and have no idea where i put it. i will keep looking, and if i find it i will post it.......
 
Matthon wrote: "What gauge wire is a typical a-body wiring harness?
Is it all the same gauge? (dash, under hood, etc) What gauge is the starter, battery, alternator wires? Just want to make sure if I am going to go up a gauge that I know where I am starting."

The various wires are different sizes, depending on the amount of current that they must carry. My suggestion would be to get a wire gauge at the hardware store, or use a calibrated wire stripper, to determine what gauge the various wires on the old harness were.

As far as the main power line is concerned (connects the battery, starter and alternator): of course it's larger than the rest. The bigger the better, because this wire has to carry the alternator's charging current. However, if you use a wire that's TOO big, it will be so stiff that you may have problems with something breaking at the alternator due to engine vibration.

"I think the bulkhead connectors are the same as the other connectors throughout the car, is this correct?"

The old bulkhead connectors will clean up just fine, and there is really no reason not to use them over again. Just clean and polish all the brass contact fingers until they are shiny, and do the same to its mating connector.

Again, it is not critical what kind of wire you use, or what kind of insulation it has, if you wrap the entire harness in fibreglass heat insulation tape, like the kind used to wrap headers. Just avoid wire with so-called "green" ("environmentally-friendly") insulation. (Not normally a problem because I've only seen that kind of wire used by the OEMs). That kind of insulation will break down after 15 or 20 years, no matter what you do to protect it. Mercedes and Volvo, for example, have had a big problem with this. Of course such problems arise long after the warranty has expired, and by that time the labor cost to replace the harness is often considered prohibitive by the original owner. I have bought two DOA cars this way really cheap and repaired the old harnesses myself, as I discussed in the post above. I'm driving one of these cars (1987 Mercedes 420SEL) and my ex got the other one (1980 Volvo 242) in the divorce and is still driving it.
 
Matthon wrote: "What gauge wire is a typical a-body wiring harness?
Is it all the same gauge? (dash, under hood, etc) What gauge is the starter, battery, alternator wires? Just want to make sure if I am going to go up a gauge that I know where I am starting."

The various wires are different sizes, depending on the amount of current that they must carry. My suggestion would be to get a wire gauge at the hardware store, or use a calibrated wire stripper, to determine what gauge the various wires on the old harness were. Or buy small rolls of 20, 18, 16, 14 and 12 gauge wire, strip a little bit off the ends of the rolls and on your old harness, and eyeball them. It should be pretty obvious what gauge they are, since normally we work only with even-numbered gauges: the various wires will probably be two gauges apart in size. But don't rule out the possibility that the OEM used an odd-numbered gauge of wire. GM did this, but I'm not sure if Chrysler did.

As far as the main power line is concerned (connects the battery, starter and alternator): of course it's larger than the rest. The bigger the better, because this wire has to carry the alternator's charging current. However, if you use a wire that's TOO big, it will be so stiff that you may have problems with something breaking at the alternator due to engine vibration. On my cars I usually use an 8-gauge wire for the main power line, but I solder a short spiral pig tail made of 12 gauge between that wire and the alternator to absorb the vibration.

"I think the bulkhead connectors are the same as the other connectors throughout the car, is this correct?"

The old bulkhead connectors will clean up just fine, and there is really no reason not to use them over again. Just clean and polish all the brass contact fingers until they are shiny, and do the same to its mating connector.

Again, it is not critical what kind of wire you use, or what kind of insulation it has, if you wrap the entire harness in fibreglass heat insulation tape, like the kind used to wrap headers. Just avoid wire with so-called "green" ("environmentally-friendly") insulation. (Not normally a problem because I've only seen that kind of wire used by the OEMs). That kind of insulation will break down after 15 or 20 years, no matter what you do to protect it. Mercedes and Volvo, for example, have had a big problem with this. Of course such problems arise long after the warranty has expired, and by that time the labor cost to replace the harness is often considered prohibitive by the original owner. I bought my 1978 Dodge D300 dually w/440 V8 really cheaply because it was DOA with a bad harness, and repaired another car that we owned whose harness disintegrated due to the use of "green" insulation (1980 Volvo 242), as I discussed in the post above, with excellent results and we are still driving both of these vehicles.
 
First of all guys, thanks for the participation.

About traveler cable, it MUST be fire rated to exist in the elevator shaft by every code under the sun, so heat will not be a real problem.The real benifit of TC is because it must stay flexible it has more strands than normal wire so the larger gauges can still be used. As I said earlier I have 18 & 14Ga. I think most of the OEM wiring harness is 20 & 22Ga.

Factory correct connectors only apply to the lighting and some of the engine accessories, for those I will be re-using the plastic part of the connectors and getting new brass for the wire ends, no pigtails here.
About the bulkhead connector, using one gives me the ability to build this system in sub assemblies, which is very convenient.

Why do this you ask. because this car will have systems that exist in very few other cars if any and a factory set up just will not do. I will either be getting a Painless fuse block or salvaging one or a couple from a modern vehicle. The six glass fuse panel is history. Also this is what I do. I love building things and I build them my way, which to is say not always the easiest way, but is the most satisfying.
Andrew
 
bremereric said:
May I ask why you are doing this. I have bought both the engine forward and under dash wiring harnesses from year-one. I paid 150.00 for the engine forward and 500.00 for the under dash. The second seems to be costly but I would say well worth it. Both come with all new wiring and factory correct connectors. The under dash comes with a brand new fusebox and firewall connection block. =P~

On the other hand I believe 20 guage wire may be too small. Most of my harnesses use 18, 16 and 14 guage plus some larger ones for the main feed to the amp meter from the engine compartment. 8)
Click to expand...
when i get to my car i will have pretty much no choice. battery being moved, will be using mad electrics ideas about alot of things, battery/alt. disconnect, efi, might also be a lock up/od style trans, relays for headlamps, electric fans/water pump just to name a few changes. can't imagine trying to wire all this to the factory harness. and being that original looking went out the window, i agree with Matt on ditching the factory bulkhead connector. i kept a ford firewall grommet assembly from a previous project for mine....
 
I've done quute a bit of wiring. When it comes time for me to do my Duster's wiring I'll be buying one of these guys kits.

http://www.spliseal.com/

Makes the wiring look pro. Also the factory wire wrap is very very close to black hockey tape. Being Canadian this stuff is abundant, not sure if it's readily avilable down south.

Riddler
 
Riddler said:
I've done quute a bit of wiring. When it comes time for me to do my Duster's wiring I'll be buying one of these guys kits.

http://www.spliseal.com/

Makes the wiring look pro. Also the factory wire wrap is very very close to black hockey tape. Being Canadian this stuff is abundant, not sure if it's readily avilable down south.

Riddler
Click to expand...
this just got added to the list of things to buy, looks like it will go a long way to avoiding some of the usual issues...thanks Riddler
 
You must log in or register to reply here.
-

Back
Top