A wiring harness is an assembly of relatively simple parts, yet its design is quite complex. The parts include insulated wire, connector housing, connector pins, a protective wrap for the harness, and mounting tabs. The pinnacle of wiring harness development was in the late 60s to late 70s, since then the wire size has gotten smaller, insulation has become biodegradable, and the metal quality in the pins and wire has become lower due to the higher used metal content in the mix. That being said, the quality of original equipment manufacturer (OEM) harnesses is much better than that of aftermarket harnesses. It is a shame to see so many people installing wiring kits in the ’60s and ’70s cars when the harshness they are removing is higher quality than what they are replacing it with. Yes, it may be cut up and abused, but with a little effort, it can be restored to its original condition.

**TIP** If you have decided to use an aftermarket kit in your classic vehicle, use the cheapest one you can find. Almost all use the same cheap wire and components; if you pay more, you’re essentially paying for the brand name.

The wiring harness is the nerve system; it handles voltage and, in some cases, digital information. Think of each wire like a garden hose; if you pinch it, then that restricts flow, which is resistance. If you have resistance in the wire or connector, then things will not work correctly. Resistance is never good, but if this is in a non-fuel-injected harness, that may not be a significant problem, but it will be in time. However, resistance is a major problem in a computer-controlled harness. In that case, the difference between 4.5 volts and 5 volts can be a significant issue and can result in many different problems. It is important to note that higher resistance in any harness will only get worse, and it can lead to harness fires.

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With computers involved, there are often data wires, also known as the data bus system. The “no bus” message on the dashboard indicates a problem with the data bus system. The data bus system handles digital information, not voltage, but ones and zeros. This is affected by RF noise, which is produced by electromechanical devices such as ignition systems, alternators, and so on. So, the wires must be shielded from RF noise. In the early days, this was done with a woven copper sleeve with wires running inside. It was excellent but costly. Engineers discovered that twisting the wires together effectively blocks RF noise. That is how it is done today. However, this makes repairing wires in the circuit very difficult, as we must shield the repair site to block noise.

What Is A Restoration?

This photo exemplifies what a harness looks like when we receive it. The next step is disassembly. We remove the pins from the connectors and the wires so that we can soak the pins. We then place the components, including connector housings, wires, and covering, in a box for storage while the pins are deoxidized. This way, we do not lose any of the components. Here is an example of what that looks like.

After deoxidizing the pins, we replace any faulty wires, solder them onto the pins, and then plug them into the connector housings. We replace any damaged connectors before we install them. When the harness is built but not wrapped, QC inspects it. If it passes, the harness is then wrapped using good coverings, and any defective parts are replaced. When fully wrapped, it goes back to QC for final testing and inspection, and then it is off to shipping. In some cases, we will apply a sealant to the connectors and the wire side. This helps to protect the pins from future oxidation.

**TIP** If you are installing high-power electrical, such as a winch, high-amp alternator, or stereo. Always run the power and ground at least 1 foot away from a harness, and if you must cross a harness, do it at a 90-degree angle.

So what kills a wiring harness? Let’s start with the number one problem we deal with.

Oxidation is the primary issue we address.

The good news is that we won’t delve too deeply into the science here; instead, we’ll help you understand the basics of oxidation and its impact on a wiring harness. So, what is oxidation? Oxidation is the loss of electrons during a reaction by a molecule, atom, or ion. Oxidation occurs when the oxidation state of a molecule, atom, or ion is increased. The opposite process is called reduction. Wait, I promised not to get into science. OK, Rust is oxidation. The Statue of Liberty is oxidized; it was once a dull brown copper color. The white, green, and blue powdery substance that forms around your battery terminals is oxidation.

Everything oxidizes, so when something looks old, it is most likely oxidized. It is not simply a color; in fact, if you can see it, then it is usually advanced. But let’s talk about its effects on a wiring harness. An oxidized wire can conduct electricity; in fact, electricity can slow down oxidation. The problem comes in when you need to repair. When your battery terminals are oxidized, you can use baking soda and water to clean them, but they are thick and they can handle that type of aggressive cleaning; connector pins require a less destructive cleaning. Thick ring terminals can be sanded to clean metal and reused, but fine or small connector pins cannot be sanded, as it would damage them.

Why is oxidation an issue?

This photo is of 2 badly oxidized connector pins. They fit in a connector housing. This is an example of what saltwater does to a wiring harness. They are from a harness that was in a hurricane. The pins cannot be saved; if we tried to clean them, the cleaning process would strip too much metal, and the pins would be too thin to reuse. Note, the attachment point is completely dissolved away; there is nothing left to solder a wire onto. This connector is scrap at this point.

A badly oxidized wire can conduct electricity, but it will have resistance, and that will cause problems. Sorry, a bit technical again, when the voltage is increased, the current or amps will go up. However, if the resistance is higher, the amps will drop, and in turn, it takes more amps to drive the circuit. In a simplified real-world application, resistance is why the wire is too hot to touch and why a fuse will blow with no explanation. Generally speaking, it takes more amps to drive a circuit; the amps go up, and the fuse pops, which protects the circuit. If you install a fuse with a larger amp rating, the wire will overheat and melt. So, it will eventually reach a point where it can no longer handle the load, overheat, and result in a short or fire. However, this point of resistance takes many years to be reached.

Oxidation becomes an issue for us because we cannot solder to an oxidized pin or wire. Here is a video demonstration of a solder attempt on an oxidized wire. In the videos, we are using over-the-counter solder, nothing special. However, we are using a 1500-watt Triton Soldering unit with carbon tips. This is way overkill for anything you would have at home. It has two advantages for what we are trying to do here. One, it is much faster than anything else, and two, 1500 watts will burn through some (not all) oxidation, which will give us the best chance at getting a good solder joint.

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Video 1

We are using thicker gauge wire here because we are trying to create the best possible chance of making a connection. The larger wire will handle the heat of the soldering iron. However, as you can see, it gets too hot to touch. Also, note that the connection is not soldered and the solder has not penetrated the wires. Also, note the color of the wire; this is advanced oxidation, and this would have been scrapped and not reused.

Video 2

The wires in this video have a clean copper color; this is what the wires should look like before you try to solder. Note the silver color of the solder and the fact that the joint cannot be pulled apart. Also, it took much less time and heat, which caused less damage to the wire. This is why we take the time to remove the oxidation. The result is a better product.

Oil Leaks:

Oil leaks are very damaging to a wiring harness, as are almost all chemicals on a harness. Engine cleaning spray can be used with caution, but high-pressure spray should never be used directly on the harness. Oil is the most common of contaminants. It damages the protective wrap and will damage the insulation of the wire, which shortens the life of the harness.

Rodents:

This is a problem that manufacturers created. Rodent damage was relatively uncommon in the early 80s and older. In the late 80s, manufacturers switched to biodegradable insulation, using soy as a base, which turned out to be a hit with rodents. Later, they developed formulas that were designed to stop the problem. It did somewhat, but it created a new problem: sensitivity to heat. More on that below. Although it looks bad, rodents usually do not chew on the connector housing, and that is what we must have or be able to recondition if we are to restore the harness.

Heat:

The second generation of biodegradable insulation harnesses was susceptible to heat. Because of this, the majority of our customers are in higher heat areas. You can pull the insulation off the wire by running it between your fingers. Check back for a video of this coming soon.

Pin De-oxidizing:

As we deoxidize a pin, it strips a microscopic amount of metal. Dies and molds wear out over time, and as that happen,s it affects consistency. Because of this, we never know precisely how many deoxidizing cycles a pin can take; we keep processing them until they are clean or too thin due to the cleaning process. As the pins become too thin, we can not reuse them, or we risk a bad connection that can cause a fire. We replace them with pins from our B-D grade inventory, and the process starts on the replaced pins. As pins are deoxidized, they are vacuum sealed, and they wait for the rest of the pins. We must work through the process to get a quality product. Then, when deoxidized, we can start building the harness. This process is what sets us apart from the rest, and it is the reason we can offer a lifetime warranty.

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