How To Find A Short In A Car (w/Pics): Extraordinary Guide

A short or electrical short is a wiring harness issue in cars. It is sometimes known as a short circuit. Electrical shorts can happen in any vehicle; learning how to find them is essential to diagnose and fix your vehicle properly.

Having an electrical short in your car can be both frustrating and dangerous. Luckily, there are ways to find a short in your car if you know what to look for. In this extraordinary blog post, we will explain how to find a short in your car, and with this easy-to-follow guide. Read on to learn more!

What is Short in a Car

Short Circuit
Short Circuit

Before we start our topic first you should know what a short is in a car. A short means a direct connection between two poles. It is a direct connection between the battery’s positive and negative power sources without an electrical current flowing through the part.

A short circuit in a car is an electrical malfunction wherein an unintended path is created within the vehicle’s wiring system, resulting in a sudden loss of power caused by an excessive amount of current flowing between two points within the circuit.

Electrons in the current bypass the component in the circuit and travel through a parallel path making a direct connection between the battery’s positive and negative power poles. In this way, all the full-energy electrons go directly from the battery’s positive to the negative pole, where it loses all the energy of current flow in the wiring causing it to overheat and burn it.

Types Of Short

1. Short to Ground

Short to Ground
Short to Ground

In the automobile world, the term “short” generally refers to “Short to Ground” which means the battery live wire touches the ground wire or metal frame directly bypassing the load in the circuit. Short to the ground suggests that the battery’s positive pole and negative pole possess a direct connection, which prevents the circuit’s original design from functioning.

A sufficient breakdown of live cable insulation could short to ground. Thus, an excessive amount of current can flow directly from the positive to the negative pole, causing too much heat in the circuit, which can burn out the circuit.

2. Short to Power

Short to Power
Short to Power

A short of electrical power is a short circuit of wiring in which a nearby live wire is connected to an adjoining live wire. The absence of power can occur in the same location where the same live wire creates a parallel path to a switch that you open. Thus, the current still flows to the component even though the switch is deactivated.

A live wire running together with a car headlight wiring within the wiring harness can be chafed due to rubbing and touches the adjacent live wire that may remain the headlight on even though the switch is off. You’ll notice this problem by pressing the brake pedal, and the headlights turn on.

Related Post: Car Electrical System Basics, Function, Working, Diagram

How To Find A Short In A Car (With a Test Light & Multimeter)

Having a car short can be a worrying and inconvenient experience. Knowing how to identify and locate a car short is an important skill for any car owner. It helps you save time, money, and stress when dealing with a problem. When you suspect your vehicle has an electrical short, you should immediately do the following. 

  1. Understanding Electrical Circuits for Troubles
  2. Look Into The Fuses 
  3. Inspect for Short Circuit 

1.  Understanding Electrical Circuits for Troubles

Blown Fuse
Blown Fuse

As an automotive technician, troubleshooting short circuits can be a difficult task. Fortunately, with the right preparation and knowledge of the circuit, it can be much easier to identify and repair components that are causing a short circuit.

Using your vehicle’s manual, you can access the wiring diagram. The wiring diagram gives you a better understanding of the circuit, how it functions and what to do to test it and find the short circuits faster. 

A blown fuse is indicative of a fault in an electrical circuit, typically due to an excessive current draw. This can be caused by a variety of factors, including increased resistance in the circuit, or a higher-than-anticipated amperage that exceeds the rating of the fuse. Therefore, when fuse amperage is too low, it can lead to a blown fuse as the device is not able to handle the reduced amount of current flow and will trip in order to protect itself from potentially damaging conditions.

In certain cases, a short circuit may not cause the fuse to blow, yet it can still lead to battery draining, and the battery experiences an elevated level of the current draw which depletes its charge over time.

Related Post: The Ultimate Guide To Car Fuse: What it is & How it Works

2. Look Into The Fuses 

Checking Short By Test Light
Checking Short By Test Light

Fuse is a highly effective method of locating electrical shorts in automobiles, due to its ability to rapidly narrow the search parameters. Moreover, it can pinpoint the exact location of a short circuit and provide further diagnostics which can be used to resolve the issue. For this reason, you should have a 12-volt automotive test light.

To begin with, figure out which parts are about to be faulted in the vehicle’s circuit. Remember that every fuse has a fuse number and can be located through the fuse number. We recommend looking up the vehicle’s manual for the electrical circuit diagram to understand the fuse number better.

We will use a 12-volt test light (and a multimeter) to identify the exact circuit for short. This will help us determine the circuit that is affected and how much damage has been caused. By following the step-by-step instructions described in this guide, you can safely troubleshoot the issue and find out what caused it in the first place.

Battery Terminal Removed
Battery Terminal Removed
  • Before we start, first turn off your car’s switch completely.
  • Disconnect one of the battery’s terminals (negative or positive terminal).
  • Attach the end of the test-light connector to the terminal removed from the battery.
  • Place the opposite end of the test light on the battery pole. If you’ve got a short, the test light will automatically turn on.
  • You can quickly find an easy-to-reach short circuit by going through the fuse one by one. You must remove the fuses to see if your test light goes out.
  • If the test light goes out by removing the fuse, you have located the circuit that contains the short. There was a problem with the fuse and its connection, which caused a short circuit.  
  • Repeat the same process with all other fuses if the test light does not go out. 

This methodology is an effective solution for narrowing down the search for potential wires from hundreds of options, to a mere few.

You can also use a multimeter (if a test light is not available) to test for short in a wire. It can be used to measure voltage between two points along the wire. This is an effective diagnostic tool for determining whether a short exists in a wire.

Checking Short Through a Multimeter
Checking Short Through a Multimeter
  • To test for short, the multimeter should be set to the 20V scale prior to conducting the tests, and one lead of the multimeter should be placed on the battery pole and the other connected to the terminal removed from the battery.
  • The multimeter should read some voltage if you have got short. Now, follow the same procedure mentioned above by removing the fuses one by one and keeping an eye on the multimeter.
  • If the multimeter reads zero volts after the fuse has been removed, it can be deduced that a short circuit is present.

Now that you have identified the presence of a short-circuit in the circuit. It is necessary to engage in a process of locating the precise source of the electrical fault. This process is commonly referred to as “tracing the short”. In the next step, we will find out the precise location causing shorts in the circuit.

3. Inspect for Short Circuit 

Shorted Wiring
Shorted Wiring

This step is to trace the circuit for short. Here you have to inspect the parts of the wiring harness. Check the chafed wiring in parts of the circuits you have gained access to and look for burned or loose wires. Also, watch out for melted insulation. 

  • Identify the various connectors, switches, wires, and every factor related to that shorted circuit. Also, remember to find the power source and ground. By analyzing the diagram, you have understood how the circuits work and what part of the circuits you have used for the tests. 
  • Physically inspect the components of the circuits you have got short and ensure they are working according to what the manual recommends. If the connection is not working properly, you know the shorts are from the direct connection of the electrical components.
  • Remove the plug or sensor socket from the load or sensor. If the test light goes out (or the multimeter reads zero volts) it means the fault lies in the motor or sensor. If the test light doesn’t go off, it means the problem is somewhere in the circuit.
  • Reconnect the plug to the load or sensor and disconnect something midway through the circuit, such as at the switch. If the test light goes out, then it means the short is somewhere between the switch and the connected load.
  • Inspect the circuit between the switch and load for chafed, corroded, and cut wires. One way to correctly trace a short circuit is by grasping the wire harness and flexing it. If the test light goes out, you know you broke a short circuit. Look for another spot to disconnect the wires and see if the test light goes out. Keep dividing by disconnecting connectors and looking out for the test light to go out. In this way, you can finally detect the circuit for short.

In the above technique by breaking down the problem into smaller pieces and using a logical way to analyze it, it is possible to find a short circuit. This method of problem-solving can be used for a variety of other issues as well, such as battery draining. With practice and dedication, this skill can become an invaluable asset in no time.

Final Thoughts 

In conclusion, the process to locate and solve a short circuit is not an easy task. It requires patience, skill, and knowledge of the circuit itself. However, if you take the time to understand the cause of the problem and follow the steps outlined in this article, you will be able to identify and eliminate any potential hazards. Additionally, it’s important to keep safety as a top priority when dealing with electricity as any wrong move can lead to serious consequences.

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