10 Problems Caused By a Bad Battery Wiring Harness

A battery wiring harness is one of the most important parts of the car; people probably already know that.

However, what purchasing manager may not know is just how frustrating a bad battery wiring harness can be. These wiring harnesses play an integral role in the vehicle.

However, because battery wiring harnesses are an integral part of the car, a bad one can make a difference. So here is a list of some of the problems your project may face with a bad wiring harness.

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1. Engine Shutting Off At a Lower Speed

One of the major problems that a bad battery wiring harness leads to is your engine shutting off. That is not to say that a bad wiring harness is the only reason your engine shuts down unexpectedly. Various other factors lead to your engine shutting down. But, the most common reason is bad wiring in the wiring harness.

Loose or corroded wires in your wiring harness can be a real cause for concern. Since the wires don’t contact the ignition circuit constantly, it does not receive the volts it needs. With the lower voltage, the ignition will not keep your engine on when it is slow.

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2. battery wiring harnessProblems Starting the Vehicle

Other than your engine shutting off at a slower speed, the car maybe will not start entirely. That is especially something that I experienced with my battery wiring harness. The inability of the ignition circuit to receive the required volts can make it very hard for the car to start.

The battery cables act as the bridge between the car’s battery and the rest of the electrical system. And when the cables do not function properly, the car will run into problems. Moreover, it takes a considerable amount of cranking power to turn an engine on. Therefore, they will need all of the help that they can get through the battery.

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3. battery wiring harnessBattery Terminal Corrosion

Battery terminal corrosion is a serious issue that nearly every driver faces eventually. The acid layer on the battery – near the cables – makes it hard to conduct electricity. The acid layer forms over time, and the main reason why the acid layer forms are because of heat. Extensive heat to the battery turns the acid into vapors, settling on top of the battery.  

The corrosive layer that forms atop the battery can increase the resistance along the contact surface. In more severe cases, the corrosion can completely block out the flow of electricity. But the corrosion does not stop on top of your battery. It can seep into the cables, making them practically useless. If you find the wire destroyed from the inside, you may have to replace the wire completely.

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4. Lights and Other Electrical Components Not Working Properly

The wiring harness is responsible for connecting every electrical part of the car to the battery. Older cars have individual wires that connect to the battery independently. Cars come with a harness, compile all of the wires in a single bundle, and connect to the battery. And while this has its fair share of advantages, the major disadvantage is that there is only one point of contact.

With only a single point of contact, problems in the battery cable can lead to various parts of the car not working. It leads to parts like lights, indicators, and dashboard lights flickering or not turning on properly. That again comes back to corrosion in wires and above the battery.

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5. battery wiring harnessConnector Damage

Other than wires eventually receiving damage over time, the connectors can also be at the receiving end of serious damage. You may not have thought that the connectors may also be a problem, but it is widespread. The connector is fairly cheaper than replacing the wire itself, so you should be sure to check that first.

Connector damage can occur due to corrosion or due to a lack of care by the driver. Finding a problem with the connector can be very difficult to spot. Sometimes, the wires can disconnect from the connector while driving, leading to various problems in your car.

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6. Damage to the Wiring Harness by the Metal Panel

Damage to your wiring harness can occur in various forms, one of which is the damage from the metal panel. Didn’t you think the metal panel beneath your car could be the reason why you have these wiring problems, did you? When going over rough terrain or going over a bump too fast, it is possible the metal case beneath your car may damage the wiring harness.

Lucky for you, while this is a very frustrating repair to get, it is scarce. It is not common for the metal panel in the front right wheel housing to disrupt the wiring harness. That said, you should not completely dismiss the idea that this could be the cause of your battery problems.

7. Water Wicking and the Damage They Cause

Did you think that water can’t cause damage to the wiring harness? Well, think again. Water can be hazardous to your harness under the wrong circumstance. One of these circumstances being water wicking. Water wicking is when water travels internally through and along the wires through cracks within the wires.

Through water adhesive properties, it manages to stick to the wires. That is especially common during colder seasons. The worst part is that water wicking travels, and it can travel a great deal. Sometimes wire wicking can spread through the length of the wire, essentially eroding the wire from the inside. The bright side of water wicking is that it can be easy to spot. It often starts from the connectors, so you can sometimes get a general idea of the corrosion by checking the connectors. In more unfortunate situations, you may have to check the entire length of the wire for damage.

8. battery wiring harnessMechanical Damage

Stress on the wire of any kind will lead to serious damage, but the wire without showing any signs of breaking. While most wires have insulation that is considerably stronger than the cable itself, this more durable insulation can also backfire. Due to the significantly firmer padding, you cannot see the damage to the wire. That stronger insulation also makes this particular failure much harder to spot and find. Wire tension or stress can also lead to wire or connector failure.

Wires can also fail when they are just long enough to reach their connectors. A short wire within a harness can be hazardous to the integrity of your yoke, as more factors could lead to its failure. Debris, thermal expansion, and even smaller impact from speed breakers can lead to your wire disconnecting from the connector.

Connectors and splices that move around, even slightly, leads to problems in the wire harness. Constant flexing of the wires also puts a lot of stress on the cables, causing them to break. You can find the problem wire by moving it around slightly and looking at short bursts of function as soon as you change their position. It would help if you also tightened your connectors and splices to avoid further wiring problems. 

Looking for sharp bends or kinks on your wires is a good way to find breaks. You can often find these bends and curves on much larger cables that can move around more freely. It would help if you also reinforce the connectors in your vehicle, as the constant movement of the wires can lead to serious damage.

9. battery wiring harnessThermal Expansion

Thermal expansion is one of the worst things to happen to your cables. Thermal expansion can shorten your wires at colder temperatures, which makes them considerably tighter. The tighter the wire gets, the more likely it is to break or disconnect from the connector. This break is harder to find due to the insulation above, which is considerably stronger than the wire itself.

To find the broken piece, try looking for places on your wire with little or no slack. And if you see sharp bends in a fence, these are places where the wire broke off from the rest.

10.battery wiring harnessHarness Damage

The insulation foam within the wires can sometimes make its way out due to various forms of damage. Sometimes the damage can be in the harness instead of the cables. From debris to impact on the vehicle, the cables can expose insulating foam for multiple reasons. This insulating foam can destroy the middle of the harness, causing problems in the wire.

This damage is often very severe, and corrosion of any cable will require a change. When changing the wires, you should be very careful when choosing a replacement. The replacement cable should be as big or even bigger than your current cable.


The cable harness of your project can be subject to a lot of damage throughout its lifespan. And if all of these problems are feeling a little overwhelming, well don’t worry, because we have just the thing for your project. At COOLM Tech, we make custom cable harnesses that you can use in your vehicles. We provide solutions to all of the battery cable harness problems that you may experience.

Hey, I am John, General manager of Cloom and OurPCB.

I am a responsible, intelligent and experienced business professional with an extensive background in the electronics industry.

Reach me at sales@wiringo.com to get a quote for your projects.

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