When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
If I were to rewire my own '38 - 1/2 ton, where would I look to find out what wire sizes to use, say to connect the fuel gauge to the sender with, or a dome light to the door button and then to what else for power?? The harness vendors make it sound real simple, like just take out my old stuff and put in their new ones, yaa-right!! Can I stay with the 6V gauges and upgrade the lights to 12V? I'd need a 12V alt. & alot of runtz's, but how do you figure that out? Tks~JH
If I were to rewire my own '38 - 1/2 ton, where would I look to find out what wire sizes to use, say to connect the fuel gauge to the sender with, or a dome light to the door button and then to what else for power?? The harness vendors make it sound real simple, like just take out my old stuff and put in their new ones, yaa-right!! Can I stay with the 6V gauges and upgrade the lights to 12V? I'd need a 12V alt. & alot of runtz's, but how do you figure that out? Tks~JH
Size your wires individually by two factors - the normal current draw, and the fuse size. Example - a light that draws 2 amps, and there are 4 lights on this wire - (8 amps total). Use a #16 wire minimum, and fuse at 10 amps. Here are some common sizes - 18 Ga - fuse at 5 amps, 16 Ga at 10 amps, 14 Ga at 15 amps, 12 ga at 20 amps, 10 ga at 30 amps. This will cover most any common circuits. Remember that the fuse is there to protect the wire as well as the load. Also pay attention to the type of insulation on the wire - the old rubber type will eventually dry and crack, some of the plastic stuff isn't to good at higher temperatures. Teflon is about the best for all but really high temps, and the most abrasion resistant. You can upgrade to 12V, but you will need dropping resistors for the gauges, or an electroinc regulator circuit to supply 6v to the gauges.
Tks Alchymist! I'm guessing to find out what the original gages need for amps, I'd have to look that up in a service bulletin and cross check it with the wiring diagram, to come up with the right sizes and fuses???!!! Is there any place that sells a 6V harness with fuses in place? Later~JH
Why don't you pull out your old harness completely, lay it out on a large flat surface, and compare the wire sizes to your new wire you buy, and go from there. You can use a 4x8 sheet of wood if you have some laying around, and use nails to spred and hold the harness out, and use this to make the new harness.
If you put a quick description on a piece of masking tape and tape it around the wires at every plug end and wire terminal, it should not be very hard. Wiring harnesses in the early years where not that involved.
If you unwrap the wires, stretch it out so it stays, then it will be a simple replace wire for wire thing. You do not need to know what every wire is for during this process. Just make sure you are methodical and don't forget any of them.
You can take small samples to the place where you are going to get new wire, and eyeball it for the correct size.