Learn how to fix the shorted wire in a car harness from this guide.
Electrical issues in a car may seem trivial, but when they’re so profound, they may cause the car to fail to function. One such issue is an electrical short of a wire in the wire harness.
The complex arrangement of wires in a harness can make it hard to diagnose which wire specifically has the short.
But if you’re facing such a problem, worry not; we’re here to help you.
Join us as we explore the shorted wire problems in engine wiring harnesses and how to fix them.
What is a Short Circuit?
A short circuit primarily means that an electrical circuit follows the shortest available route rather than the path it should follow.
It happens when a wire in the harness takes another path to transmit the power.
The problem is serious and can cause your car to stop functioning.
But it’s not the only electrical issue you’ll likely encounter in your car’s engine wiring harness.
You may also experience an open circuit issue, which primarily means that there’s a point where the electric current is not flowing.
An open circuit is as serious as a short, but often, a short circuit is the most common issue.
How does an Electrical Short Circuit Happen?
A car overheating due to an electrical short.
Take the case of an engine wiring harness encasing numerous wires, each sending current to a particular destination.
Now, if two or more wires are open or have a break, they could come into contact.
Such a scenario will create a short circuit problem. The current will flow through the shortest route, resulting in overheating of the conductor.
If the overheating is so intense, it will result in an electrical fire as the hot wire also burns the neighboring ones.
Types of Short Circuits
Short Circuit in the Car.
There are two types of short circuits:
Short to Ground
It happens when the current fails to take its intended route and flows into the car’s body/casing. Often, this happens when the car wires are next to the hot components, such as the engine.
This results in the charring of the car wires, exposing the conducting part.
When this comes into contact with the metallic parts of the car, it results in a short. Such a short-to-ground issue is serious and can often lead to blown fuses.
Short to Power
It occurs in a scenario where numerous wires are covered in a harness.
When two or more wires are broken and come into each other, it will result in a short-to-power problem.
While wires in a harness may appear safe and protected from external elements, they can still have broken parts.
For instance, take a case whereby you’re installing an aftermarket device on the car’s body.
When screwing an electronic component, the screw can pierce the wires and connect the numerous conductors creating a short circuit.
A short-to-power issue may result in the car outputting a different function than it should.
For instance, when you switch on the headlights, you may have the horn instead blowing and such other issues.
Signs and Symptoms of a Vehicle Short
A Mechanic Checking for a short circuit.
- If you’re experiencing a low voltage when trying to start a car, this could be a sign of a short circuit. A short circuit could also be an issue if you have longer cranking time than usual.
- Also, if your car requires jumpstarting in the mornings or when it has been parked for long, you’re probably having a short.
- When your car lights dim during engine cranking, you’re probably dealing with a short circuit.
How to Find a Short Circuit
A mechanic finding a short circuit.
Locating a short in your car may take quite a lot of time as the issue can be highly concealed.
Primarily, you’ll require an electrical wiring diagram (EWD) to assist you in navigating through the electrical systems.
In addition, you need a tester/multimeter and a screwdriver to open the casing covering the electricals. Next, follow the steps below to locate a short.
Check the EWD
You need to map the car’s electrical system using the EWD as your guide. First, remove the wiring harness to expose the wires.
Next, using the EWD, identify the various wires represented in the diagram by their color codes.
Ideally, your car’s wires should be coded like the EWD. It helps you identify the respective wires and their functions.
Inspect the Fuses One-By-One
A Car Mechanic Testing the Fuses.
Fuses are among the components most likely to blow when there’s an electrical short.
Hence, checking out which is blown helps you work back to the wires with the short issue. Here’s the procedure:
- Take a fuse at a time and connect a tester to one end and the other to the electrical system.
- If the test lights go on, then the fuse has no problem.
- But if it doesn’t, it means the fuse is blown. Follow its electric circuit to see where there’s a likely electrical short.
- Check out each of the fuses individually using the above procedure.
Locate Faults Along the Wire
Do you have a particular wire you suspect could be the issue?
You can test it, but first, you will need to disconnect it at the load endpoint or sensor.
Next, using a test light, confirm if the electrical current passes at the sensor or load section.
For instance, you suspect that the wire has a short, near load, such as a headlight.
Simply remove the load, place the test light near this point, and check if the current is passing.
Inspect the Wiring
A broken car wire harness.
Conduct a visual inspection of the wire and check for points where it could be broken.
If you identify a frayed/chafed wire, this should be a point of focus.
Replace or repair the frayed wire and test if it’s effectively conducting current.
The issue is that most car wires are not exposed. Hence, you may struggle to locate it when you open the panels, but it’s still a viable diagnostic option.
5V Circuit Testing
The engine control module (ECM) utilizes a 5-volt circuit to control the car’s engine. You should also check out if it has a short circuit problem.
Start by disconnecting the battery and then the ECM.
Next, test via a multimeter if there’s a current between the circuit and the body.
Confirm whether a current flows between the circuit and the car engine.
How to Fix a Short Circuit
Taping a car’s electricals.
There are two main options to fix a short circuit problem.
How to Fix Shorted Wire in Car Harness: Tape the Exposed Wire
Take a case whereby, after diagnosing the cause of the short circuit, you realize there is a broken part in the wire.
One of the easiest quick fixes would be taping the part with electrical tape to ensure you insulate the conductor.
But this is a short-term fix, and you will need to replace the wire in the long run.
Alternatively, take the option we’ll discuss below, as it’s also a permanent fix solution.
How to Fix Shorted Wire in Car Harness: Install a Connector
The method involves using a wire cutter to remove the exposed part perfectly.
Next, link the two parts via a connector and test if the joint is a perfect conductor.
How Can You Prevent a Short Circuit?
Most short circuit issues can be prevented by taking key measures to ensure the issue doesn’t happen.
Here are some of the precautions you should undertake:
Ensure there’s no Moisture
Moisture in car electricals.
Contact between water and electricity results in a shortcut circuit and other electrical issues.
Hence, always dab your car engine area with a dry cloth or sponge after a visit to the carwash or a drive in the rain.
Check Individual Wires Often
A simple inspection of the wires can go a long way in preventing most short-circuit issues before they get out of hand.
Make a habit of looking for possible breaks, cuts, tears, and wear on the wires.
Also, ensure your mechanic thoroughly checks the car’s electronics during service visits.
Don’t Overload
Overloading the car’s electrical system is among the cardinal causes of electrical shorts.
When the load is higher than the system can handle, it results in overheating of the cables.
The extreme temperature can also cause some parts to blow out, exposing the wires to probable contact with other wires.
Check Devices Before Connecting
Inspect all aftermarket components for possible short circuits before installing them onto the vehicle.
If they already have shorts, they’ll transfer the issue to your car, which can increase into a bigger problem.
Summary
Fixing an electrical short can be expensive and may cost up to $200. It all depends on where the short is located and the affected parts.
But car shorts are preventable when you take the measures in this blog post.
Most importantly, fix a bad wire issue immediately after detection to prevent it from becoming a big problem.
Thanks for your time, and good luck with your car.
