Wiring from scratch

[BIGglaSS]

I'm about to start wiring my 57 restomod truck with LS swap (2004 - 5.3 engine). I spent a couple days reading on the internet, and got even more confused. Please bear with me, this will be long. If anyone knows of a good article to read when starting from scratch, please point me in the right direction. Thanks in advance.


What I have so far: AAW classic update harness, and a battery mounted under the cab to the right frame rail. They supply NO instructions or wiring to get power from the battery to the new harness, or how to hook up an LS swap. I'm completely confused on how to rout power between the Battery / Fuse block / Alternator / Starter, and Engine harness.

1. If I understand correctly, the starter is connected DIRECT to the battery without any sort of fused protection? If so, what size cable would be required to go 6' from the battery to the starter? I have NO idea how many amps the starter pulls. I have selected a 1/0 cable, but not sure if that is enough for a 6 foot run.

2. I can't figure out where to run the alternator output wire to. The AAW harness, the starter, or a junction block near the battery? Which end of the alternator wire gets a fuse? Near the alternator, battery, or both ends? Or, is the alternator controlled by the engine harness?

3. There are NO provisions on the AAW fuse block for relays. I'm assuming I will need to build a relay box (Wired directly to junction block?) What should I plan to use relays for? Here are some electrical items that will be installed.
- Radiator Fan
- A/C
- Power door locks
- Headlights
- Fuel pump
- Anything else I missed?

4. I know nothing yet about building the engine harness. Where does it get it's power supply from? What size fuse would be required for the engine harness?

My first goal is just to get the engine to run so the truck can move under its own power. (Hook up the battery, alternator, starter, and engine harness). Then I will permanently add to the rest as I figure it out. Thanks to anyone that can help.

[BIGglaSS]

I may have figured out part of #1. Working backwards, the battery is 800 amp. A 6 foot 1/0 cable @ 800 amps will lose 0.5 volts. I think that is acceptable? Assuming the starter pulls way less than that.

[PGSigns]

That will be plenty of cable for the starter. Ground cable the same size. Will try and address a couple of your other questions. For your LS you need to decide who's harness you plan to use (I am going to use a Holley terminatorX harness). The harness instructions will answer a lot of your questions.

1. If I understand correctly, the starter is connected DIRECT to the battery without any sort of fused protection? If so, what size cable would be required to go 6' from the battery to the starter? I have NO idea how many amps the starter pulls. I have selected a 1/0 cable, but not sure if that is enough for a 6 foot run.

2. I can't figure out where to run the alternator output wire to. The AAW harness, the starter, or a junction block near the battery? Which end of the alternator wire gets a fuse? Near the alternator, battery, or both ends? Or, is the alternator controlled by the engine harness? Will be determined by the alternator. I would run it to a terminal block to allow power to be pulled from it and then directly to the battery. #8 wire, no fuses.

3. There are NO provisions on the AAW fuse block for relays. I'm assuming I will need to build a relay box (Wired directly to junction block?) What should I plan to use relays for? Here are some electrical items that will be installed.
- Radiator Fan May be in the engine harness
- A/C That wiring will be determined by the AC kit you use for the truck.
- Power door locks should not need a relay
- Headlights The AAW harness has that covered
- Fuel pump May be in the engine harness
- Anything else I missed? Yup picking a lot of the stuff you plan to use. All this comes together to develop the wiring plan.

4. I know nothing yet about building the engine harness. Where does it get it's power supply from? What size fuse would be required for the engine harness?
This will get the plan started on wiring the truck. I would find someone who really knows wiring to help you wire the truck. The entire harness gets planed out before the first wire goes in. Then all the hardware gets placed and installed and wiring gets run to it. Make a drawing and take notes as you go. Take your time and never let the smoke out of the wire.
Jimmy

[BIGglaSS]

Thanks. I'm using the stock engine harness from the donor.

Meanwhile, I found a site that recommends 1/0 for battery - starter (Go up one size for long runs or high compression engine) and 4awg for alternators up to 180 amp.

However, I have to run nearly 10' from alternator to battery. The charts say to use 2 awg for 150 amps @ 10', which seems overkill.

Why no fuse? If the wire gets chafed, shorted or damaged, wouldn't you want to protect it from the battery and the alternator? Thus needing fuse on both ends, or fusible link.

[PGSigns]

Well you have to pull out a lot of things from the stock harness. There are folks that will modify it for you if you don't have the background to do it. Just because you have a 150 amp alternator does not mean you will ever have a 150 amps of load. Wire size is calculated on load and duty cycle. The reason for no fuse is that if you fuse it for the 150 amps then you really have not protected it for the reasons you are thinking. The best protection is good wiring practices. The fuse box provides the protection to all the circuits that you run. Your final configuration for you engine harness will have a small fuse and relay box for the engine harness.
Jimmy

[VetteVet]

PGsigns has given you great advice.

Here are some diagrams that should help you design your harness.

The first one is an original that shows how to wire a truck with the battery in the back and it uses a voltmeter. The large battery cable from the rear of the truck is not shown going to the starter , but it goes to the main junction and then he had to run another cable from there to the starter. I show this in the next diagram which has the batter in the normal spot.




This one I modified to use with the battery gauge that came in our trucks.




Here is an excellent diagram to illustrate the relay wiring which your harness may not have but it is simple to run the control and power wiring from the main distribution block (main junction) to them and then to the fans, AC, fuel pump, lights etc.

[BIGglaSS]

Excellent, this was helpful. I'm thinking about mounting the battery on the firewall to reduce the wire runs. Though instead of fusible links, I prefer fuses. Easier to replace if needed.