scratch wiring how to

[grinch]

Hey guys, I'm new here but been keeping up with you for a while. I've been building a 42 Ford rat truck for the last year or so and I'm not far from having it ready to go. I haven't taken pictures of the build through all of its stages like some others and I can't offer much as far as that goes.

I've noticed that alot of questions come up about what wiring harness to use and so forth, so I thought it may be beneficial to show what the underemployed do when they have more time than money.

I've used a Painless Wiring kit before and felt the quality was top notch, however, I felt as though I spent a bunch of money on it just for someone to label the wires for me. I hope I can show you guys a few tricks that may help and I hope that anyone else out there with input on this to please comment or share............I have already missed a few things, so the comments will help keep this all straight.


I started with a fuse box/panel from an 81Chevy Truck. I took all of the wiring and plugs inside the cab that was attached to the fuse box. I paid $10 for it and felt raped, but I needed it to get started.

 

[grinch]

Keep the plugs on the ends of the wires if possible..........IT WILL MAKE IT EASIER TO DETERMINE WHAT WIRE IS GOING WHERE!
What I mean is........if you know what plug mates to the headlight switch, then you know what wires mate to the headlight switch.

Most of this stuff is common logic if you take your time.

At this point you have to get some of this nest of wires figured out and labeled up. I did have to cheat a little using a 81 Chev truck wiring diagram and fuse panel configuration diagram...........Some of the labels on my fuse panel are worn or faded.

 

[grinch]

pics didn't post........let's try again

 

[acourtjester]

wire marking

HI Grinch
here is a post I did about a week ago same idea I hope it helps.
http://ratrodsrule.com/forum/showthread.php?t=16072
have fun
Tom

 

[grinch]

I've done the same labeling Tom but they sure are proud of that tape that goes in these label machines.

The clear heatshrink I have is in a 3M HeatShrink kit that came from NAPA. NAPA has an electrical products catalog that has all kinds of stuff in it, but you will probably have to ask them to see it.

Anyway.........moving on with the project!

I continued the sorting and cleaning up of the bird's nest and used a few junction blocks.

 

[grinch]

I really wanted to be able to match all of the wire colors from the junction blocks to the terminations, however, my budget right now is not allowing it. So after doing a little shopping at Lowes and Home Depot I found where to buy wire cheap. They both have 14ga., 12ga., and 10ga. stranded wire in a few different colors and priced at .28, .30, and .36 cents a foot. I bought about $25 worth of 14ga. and 10ga.

A bit of overkill on some of the circuits, but I had to work with the combo of colors I already had and then what was available at the HD.

I should also mention that all of my switches will be behind the passenger side seat so that they won't be seen. The fuse panel will be mounted under the dash on the passenger side. Because of all of this and hiding the wires, I had to make some rather long harnesses and thus the need for some of the heavy gauge wire.

I mounted the fuse panel and then pulled one wire to the switches to determine the wire length. Then I grouped the wires by what switch they went to and then pulled them tight to heat shrink.

 

[sneakysnake]

Grinch, reminds me of mine, marker and masking tape.LOL I used the harness from a Geo metro so I could use the column switches(head lights,dimmer, wipers,signals) and they all run on relays so I two fuse boxes and a relay box.After I separated the EFI from the harness I had a rats nest.LOL

 

[grinch]

To keep things as simple as possible I broke things down like this........

The ignition switch has four wires: Battery, Ignition/Coil, Starter, and Accessory. I made one harness for these wires to travel from switch to the terminal block on side of fuse panel.

The headlight switch harness has six wires: 12v, high beam, low beam, taillights, and two other wires going to fuses. (one is fused for headlights but goes to switch, and other is fused for running lights).

The headlight harness goes from the terminal blocks/ fuse panel up to headlights and has five wires: high beam, low beam, left turn, right turn, and fan. At the front I spliced both the high beam and low beam because you must have both wires going to both headlights. I also added a ground wire into the harness in the front only and it will serve as a ground for both headlights and the fan.

 

[acourtjester]

info

HI
Things to think about when wiring you rod.
If you can run circuits through a relay that are heavy current users.
Like head lights, Starter solenoid, fuel pump, fans, and A/C units.
Using the key switch to power the relays and the relay to power the other circuits. This way you supply good current to the heavy current circuits and low current of many circuits through the key switch. These 12 volt 30/40 amp relays are on Ebay for like $12 for 20 relays. If you try to power all the circuits through the key switch it will burn out faster. And the same is for the light switch this also helps to make you head lights brighter. When you buy wire use wire that is made for autos, it has smaller size wire to make up the wire gauge and is much more flexible. You can make a rack for relays and run the circuits through the fuse panel for safety too.
Attached is the color code for a GM steering col.

Have fun
Tom

 

[eyesore]

I know you're trying to save money and prove a point but there are really decent bare bones systems for around $150 that include most switches, relays etc. Is it worth saving even $100 on something so important that could possible burn up your whole project? Just a thought!

ISore

 

[acourtjester]

my money

I know your trying to help but I spend my money wisely. It is nice if you have plenty and want to buy a kit. The US Navy trained me for communications electronics. Worked at the Kennedy Space Center on Apollo 7 through 11 and I spent 30 years maintaining CAT and MRI systems for a major manufacture. And I just love doing it. Life for many is much more then plug and play.
Y’all have fun now hear.
Tom

 

[grinch]

Thanks for the insight on the relays Tom. I'm running two relays........one for the fan and other for elec.fuel pump and they are the only two added circuits powered from the Ign. switch. My headlights are wired directly to the batt.post on the starter with a 10ga. wire which was how GM did it on the 81 trucks (actually they used a 12ga. wire). I am using the factory headlight switch which came from the same donor as the fuse panel, however, if this seems to be a problem, I'll solve it with a relay at that switch as well. I'll also agree that the automotive wire is much more flexible and I have some of it incorporated into my harnesses, however, I just didn't have the variations in colors/wire size that I needed and thus my reasoning for some of the wire from the HD. My main purpose on this project is of course to wire the rod on a tight budget but, I would have much rather had all of the wiring to be color matching automotive wire.

Isore..........believe me, I checked out all of the wiring harnesses available before making the decision to go to scratch built. I wired a truck about 5 years ago using a Painless Wiring harness, and I'm convinced completely that wiring from scratch is just as easy. The only real difference is that I have to determine the needed wires for the circuits and label them. I've wired so many race cars, making my own harnesses, that I already had most of what I needed to do the job. I'm not at all worried about burning up my project, as this is really not that complicated. The point is that if you have ever wired one vehicle using an aftermarket wiring harness, then there is no reason you couldn't wire one from scratch and save a little money if you have the spare time.

Thanks for the comments and helping me keep my thoughts together. I did finish up wiring the alternator and the headlights tonight. I left the camera at home, but I'll get some pics tommorrow. The worst part of this was trying to hide the butt connectors tying the harness into the headlight pigtails. I really should have made the harness about one inch longer on both sides. I did also forget to add the last piece of heat shrink on one side prior to crimping the butts.

 

[grinch]

I made two more harnesses tonight.

I made the harness going from the switch panel to the rear of the chassis.
It has 5 wires: Fuel Pump, Tail Lights, Rt. Rear Turn, Lt. Rear Turn, and Fuel Tank Sender.

The other harness goes from the switch panel to guages & turn signal switch.
It has 4 wires: Rt. Rear Turn, Lt. Rear Turn, Fuel Tank Sender, and Interior Light (dome light under dash).

This makes a total of 7 seperate harnesses now. To clarify, that would be 7 different groups of wires and each group is heat shrinked from end to end.

I've described 5 of these so the 2 that are left out are the Alternator harness and the Starter harness.
The Alt. harness has 3 wires: Two wires go to batt. post on the starter and one goes to the volt gage.
The Starter harness has 3 wires as well: Starter Batt. post, Start post, and Coil. These wires terminate at the terminal block where they match up to the wires coming from the Ign Switch harness.

I hope that by breaking it down like this, it simplifies the process for others. I will try in the end, to develope a diagram or schematic that I can post.

 

[grinch]

I was just going through my notes and it looks like I have to make one more harness and that will only contain the temp. sending wire, and oil press. sending wire.

The only circuits left to complete after all of this, originate at the fuse panel and stay under the dash (12v for guages, 12v for turn/signal switch, lights for guages, and horn.) (I am using the original wiper motor which is vacuum operated and not electric)

I was hoping to fire it up for the first time this wkend. and take a quick trip around the block. I think one little thing may hold me up...........brakes!

 

[acourtjester]

simple wiring diagrams

here are 2 drawings I did for the wiring of most street rods.

 

[grinch]

Tom those are awsome! I don't have to do it now!
I thought I would have the thing finished up today, but had a little plumbing problem to take care of at the house. Hope to get some stuff done tommorrow afternoon, but it'll probably be a few days before I can take her out for a test spin..........they're calling for rain the next 3 days.

 

[acourtjester]

column connections

I posted a wiring list for a GM steering column connections but found out today it was wrong.
here is the correct color code and hook up info for column.

 

[grinch]

Tom, I'm using one of those generic turn signal switches that clamps onto the column. I had to do a little thinking to make it work, but I got it figured out.

The wiring is done with the exception of the horn....(I just haven't decided what I'll be using for a horn yet.)

I've been busy trying to figure out why I can't get the engine to run. It has baffled me, but I think I've figured out that the problem is due to a lack of compression! PITA!

I'll get back to explaining how I wrapped up the wiring once I figure out if I'm going to have to pull the motor. What makes it so bad is that EVERYTHING is hooked up now and will all have to be disconnected. My clearances are so tight that I have to pull the cab to remove the motor and trans.

 

[grinch]

Wow! This project has taken a turn for the worse. Had to pull the motor & trans. and man what a pain. Looks like I'm down for a few weeks......I'm going to have to have some machine work done.

 

[billy]

I know your trying to help but I spend my money wisely. It is nice if you have plenty and want to buy a kit. The US Navy trained me for communications electronics. Worked at the Kennedy Space Center on Apollo 7 through 11 and I spent 30 years maintaining CAT and MRI systems for a major manufacture. And I just love doing it. Life for many is much more then plug and play.
Y’all have fun now hear.
Tom

um
i think you may just have a handle on this wiring stuff.....