What Causes A Wiring Harness To Fail?

Wiring harnesses are critical components in modern vehicles, serving as the nervous system that connects various electrical components and systems. While these harnesses are designed to be durable, they can still go bad or fail over time.

Why Wiring Harnesses Go Bad

Image Credit: CraftCustoms

There are several reasons why wiring harnesses in vehicles can deteriorate and fail – below we’ll explore a few of the most common. Keep in mind that maintenance and early detection can help you avoid some of these issues.

Wear and Tear

One of the most common reasons wiring harnesses go bad is simply due to the natural wear and tear that occurs over time. These harnesses are subjected to constant exposure to temperature fluctuations, vibrations, and mechanical stress as a vehicle operates. Over years of use, the insulation around the wires can degrade, leading to exposed wires, fraying, and eventually, a complete failure. Regular inspections and preventive maintenance can help catch these issues early.


Corrosion is a pervasive enemy of electrical systems in vehicles. Moisture, salt, and other environmental factors can cause the connectors and wires within a wiring harness to corrode. Corrosion not only weakens the wires but also increases electrical resistance, potentially causing electrical malfunctions and disruptions in various vehicle systems. Proper rust prevention measures and keeping the vehicle in a dry environment can help mitigate this issue.

Electrical Overloads

Electrical overloads can occur due to a variety of reasons, such as faulty components, damaged sensors, or a short circuit. When a wiring harness experiences an electrical overload, it can cause excessive heat and damage to the wires and connectors. This can lead to melting or burning of the insulation and, in severe cases, a complete harness failure. Regular diagnostics to identify and fix electrical problems promptly can prevent this issue from worsening.

Rodent Damage

Surprisingly, rodents can be a significant threat to your vehicle’s wiring harness. Mice, rats, rabbits, squirrels, and other critters often seek refuge in warm and cozy engine compartments. Unfortunately, they also have a penchant for chewing on wires, using them as nesting material, or causing other forms of damage. Rodent-induced damage to a wiring harness can be particularly tricky to diagnose, as it may manifest as intermittent electrical issues. Employing rodent deterrents and inspecting your vehicle for signs of rodent activity can help prevent such damage.

Find Your Standalone Wiring Harness At Karl Kustoms

At Karl Kustoms, we carry many different LS wiring harnesses, including these popular options:

If you have questions about wiring harnesses or anything else, contact us at 866-697-8615 or online. Our knowledgeable staff is always eager to help!