Our first tip is extremely important, and it's one you've most likely heard more times than you can count-read the instructions! Yeah, we know it's not in our nature to do such a thing until we're hopelessly dazed and confused. But when it comes to a job like this, you just have to swallow your pride. Now that you've agreed to that, here's some terminology you may want to become familiar with.
Volts, AMPS, And OHMS
In order to fully understand how the wiring in your car works, let's take a look at the element we're trying to harness-electricity. The three most basic units in electricity are voltage, current, and resistance. Voltage is measured in volts, current is measured in amps, and resistance is measured in ohms. A simple analogy to help understand these terms are plumbing pipes. The voltage is equivalent to the water pressure, the current is equivalent to the rate of flow, and the resistance is like the inside diameter of the pipe.
Getting a little more specific, voltage is the force that pushes electrons-or units of electricity-through a wire. It is a function of the electrical source, which, in our cars, is a battery. While some late-'30s to early '50s cars may still have an original six-volt system in place (sometimes even a positive-ground arrangement), it's safe to say that if you're rewiring your hot rod project, it's likely getting a modern 12-volt, negative-ground system.
There are lots of high-quality...
There are lots of high-quality aftermarket wiring harnesses on the market these days, but in this instance Candy and I chose to use this Bare Bonz system from Ron Francis. The Bare Bonz kit fit the bill perfectly for the King-T because it's a compact, easy to install unit that provided us with just enough circuits for a bare bones setup (basically all we needed here was ignition, instruments, and lights), yet it does have room for expansion if needed in the future.
Current is the volume of electrons moving through a wire or circuit. Measured in amps, it will be dependent on voltage and resistance. The resistance in any given circuit is a physical characteristic of the electrical components involved. All components will have a certain amount of resistance, although the resistance in wires, switches, and fuses is typically rather minimal.
When discussing resistance, the natural segue is to define conductors and insulators. Basically, a conductor is something that current can pass through; an insulator is something it can't. Consider these scenarios: If you ground a stereo to a plastic dash, it won't work because the plastic is an insulator; ground it to a clean metal surface and it will work. Note that we say "clean" metal because paint nearly always acts as an insulator.
Not to confuse the issue, but there are situations when something can be either an insulator or a conductor. The human body is an example. If you touch both terminals of an automobile battery, nothing happens because you have sufficient resistance that 12-volts can't overcome. But if you've ever grabbed the spark plug wire on a running engine, it didn't take long to discover than 20,000 volts was more than enough.
The Components
A typical aftermarket wiring harness consists of about 47 miles of wire, give or take a dozen or two miles. Thankfully they're usually different colors and labeled to boot. (GM color-coding is most common, but other color systems are available too.) Also included in most kits are a fuse panel, fuses, terminals, connectors, and typically a variety of relays. The instructions will tell you where and how to hook everything up, but may not spell out what everything is and does. So let's take a look at the various components and learn their purpose.