5 Reasons that cause a engine wiring harness to go bad

An engine wiring harness is an essential component of a vehicle’s electrical system, connecting various sensors, switches, and components to the computer that controls the engine. Over time, the wiring harness can become worn and brittle due to exposure to extreme temperatures, vibration, and other elements. This can cause the wiring to break, fray, or lose its insulation, leading to shorts and electrical issues. Additionally, corrosion can occur due to moisture and salt buildup, which can cause connections to fail. Furthermore, wiring can be damaged due to rodents chewing on them, which can cause shorts and other damage.

Electrical Overload:

Wiring harnesses can be overloaded by too much current running through them. This can cause the wires to overheat and eventually burn out.

An electrical overload occurs when an electrical device or circuit is subjected to a power demand beyond its capacity. This can happen in a wiring harness when too much current passes through it, which can cause damage to the wiring harness and the components connected to it.

If the current exceeds the rated capacity of the wiring harness, then the wiring insulation can be damaged and the connectors can become loose. This can lead to short circuits, arcing, and even fire. Also, excessive current can heat up the wiring harness, causing its insulation to melt, and ultimately leading to a breakdown of the wiring.

All of these causes of electrical overload can lead to a wiring harness going bad. It is important to ensure that the wiring harness is not overloaded and that the connections are secure. This will help to prevent any damage that could occur due to an electrical overload.


Corrosion can occur over time due to exposure to moisture and other environmental conditions. This can cause the wires to become brittle, swell and eventually break.

Corrosion is a serious problem when it comes to wiring harnesses. It can also cause pinholes in the insulation, which can lead to short circuits. It also causes a decrease in the conductivity of the cables, which reduces the performance of the system and can lead to malfunctioning of the equipment.

The issue is caused by a number of factors, such as exposure to moisture, extreme temperatures, and the presence of corrosive chemicals. Moisture is the most common cause of corrosion and is usually caused by condensation, which accumulates on the wiring harness and other components. Extreme temperatures can also cause corrosion, due to the expansion and contraction of materials. Corrosive chemicals, such as salt, can also cause corrosion, as they react with the metal and cause it to corrode.

To prevent corrosion and ensure the longevity of wiring harnesses, it is important to keep them dry and clean, and to inspect them regularly for signs of corrosion. It is also important to keep them away from extreme temperatures and to avoid the use of corrosive chemicals. By taking the necessary steps, you can ensure that your wiring harness remains in good condition and continues to operate properly.

Poorly Made Connectors:

Poorly made connectors can cause wiring harnesses to go bad. These connectors may be cheaply made and not be able to withstand the electrical current that is traveling through the wiring harness.

The low quality connectors can cause a wiring harness to go bad for several reasons. When connectors are made with poor quality materials, they are more prone to shorting out or otherwise malfunctioning. They can also cause corrosion, which can lead to electrical malfunctions and even fires.

Additionally, poorly made connectors can cause the wires in the wiring harness to be pulled out of place, leading to improper electrical flow and, again, failure. This is especially true when the connectors have sharp edges, which can cause the wires to fray and become damaged. If the connectors are also not properly connected, the wiring harness can also be damaged as the wires can be pulled out of place.

Poorly made connectors can also cause improper sealing of the connectors, which can lead to dust, dirt, and moisture entering the wiring harness. These contaminants can cause corrosion and other electrical malfunctions. Furthermore, poorly made connectors can cause pins to be pushed in too far, which can lead to electrical shorts and other electrical malfunctions.

For all of these reasons, it is important to use quality connectors when making a wiring harness. Quality connectors will help to ensure that the wiring harness will be reliable and safe.

Wear and Tear:

Over time, the wiring harness may wear out due to regular use. This can cause the wiring harness to become worn, damaged, and eventually go bad.

Heat and vibration can cause connectors to loosen over time, leading to poor connections. This can cause poor performance, electrical shorts, and even fires. As connectors become worn, the insulation around the wires may also become cracked and brittle, allowing for corrosion to occur. This can lead to a short in the wiring harness and cause further damage down the line.

Exposure to moisture and dust can also cause a wiring harness to go bad. Moisture can cause corrosion of the wires and connectors, leading to shorts and improper connections. Dust can interfere with proper connections or even cause a short.

In addition to environmental conditions, improper installation or repair can also cause a wiring harness to go bad. If a technician is not properly trained or experienced, they may not use the correct components or techniques. This can result in improper connections, improper insulation, and even damage to the wiring harness.

Poorly Installed Wiring Harness:

The most common cause of a wiring harness going bad is improper installation. Wiring harnesses should be installed correctly and securely in order for them to work properly and safely. If a wiring harness is not installed correctly, it can cause the wires to become loose and the connections to become corroded. This can lead to electrical shorts and sparks, which can cause a fire.

In addition, wiring harnesses that are not installed correctly can also lead to problems with the connections between the components of the electrical circuit. Poor connections can cause voltage drops and create an environment where the circuit is not receiving the correct amount of power. This can lead to electrical problems, such as blown fuses and circuit breakers tripping.

Finally, poorly installed wiring harnesses can also lead to other issues, such as corrosion and water damage. If the wiring harness is not properly sealed and protected, then water can get inside and cause corrosion.

In summary, poorly installed wiring harnesses can lead to a variety of electrical problems, such as shorts and sparks, voltage drops, blown fuses, circuit breakers tripping, and corrosion. If a wiring harness is not installed correctly, then it should be replaced as soon as possible to avoid any further problems.