How to Find a Short Circuit in a Car?

Open circuits and short circuits are two electrical malfunctions that can affect the proper functioning of the electrical components of a car. However, an open circuit has lesser risks compared to a short circuit.

While an open circuit has no current flowing to the intended components, a short circuit has current flowing in the wrong directions. This can be disastrous if you fail to rectify the problem.

Therefore, understanding how to find a short circuit in a car will help you avert the dangers of this electrical malfunction problem.

How do electric circuits work?

How do electric circuits work?

A vehicle’s electrical system works in the similitude of the body’s circulatory system. You can liken the battery to the heart, while the electric current represents the blood and the wires through which the current flows represent the blood vessels.

The electric current flows in one direction from the battery to other electrical components in the vehicle. The current flows from the battery’s positive terminal to the components and returns through the negative terminal.

The electric circuit serves as a route through which the current flows in the appropriate direction to reach the various electrical components in the car. The current is expected to maintain a continuous flow through the complete loop created by the circuit.

While current flows through the wires, it encounters resistance due to the amount of electricity the wires can conduct. If the resistance from the wires is too high, it can lead to excessive heat. Meanwhile, when there is a short circuit, the current will flow in another direction which can be risky.

Types of Short Circuits

There are basically two types of short circuits in a car. In both cases, electricity flows in a direction that is not intended. They include the following:

How to Find a Short Circuit in a Car

Short-to-ground circuit

The ground represents a vehicle’s body. Therefore, a short-to-ground circuit is a situation where current flows from the circuit to the vehicle’s body. In this case, a wire may separate from its insulation and contact the vehicle’s body or engine.

When this occurs, it can alter the lights or motor operations and blow the fuses. In addition, a short-to-ground circuit can damage different electrical components in a car.

Short-to-power circuit

A short to power circuit occurs within a wire harness with various circuits around close proximity. The short circuit alters the connection of a particular wire and causes it to interrupt the operations in another connection.

For instance, if you mistakenly drive a scroll through a wire, connecting it with another wire, the operations of the first wire may trigger the operations of the second wire. This is why you can engage the headlights in some cases, and it will trigger the reverse light at the same time.

How to Find a Short Circuit in a Car

Finding a short circuit in a car requires using either a multimeter or a 12V test light to check which fuse has the connection with the short. Once you identify the short circuit, trace the exposed wire and tape it properly.

Meanwhile, in order to use the tools recommended above, you need to know how to find a short in a car with a test light or a multimeter. However, the procedure below will help you understand how to find a short circuit with a multimeter.

Step 1: Disconnect the Car Battery’s Negative Terminal

At the outset, ensure to disconnect the negative terminal on the battery to commence the process. After that, separate the cable from the terminal. Finding a short circuit can be time-consuming; hence you have to be patient.

Step 2: Engage the Multimeter

Set the multimeter on 10 amperes and place the red probe lead on the battery’s negative terminal cable. Then place the black probe lead from the multimeter on the battery’s negative terminal.

Step 3: Check the Multimeter Readings

After connecting the multimeter properly, check the reading on the meter. If it reads nil or 0, reset the multimeter to 9 and recheck. Continue to lower the multimeter setting by one number until you get to 0. While you do this, ensure to check the readings.

If the meter does not read a draw, the car doesn’t have a short circuit. Meanwhile, if it reads a draw, it is a sign of a short circuit.

Step 4: Detach the Fuses One-by-one

Get an assistant (a friend) to help you detach the fuses one after the other while you hold the multimeter connections in place. Check whether the meter reads 0 as your assistant detaches each fuse. The fuse that reads 0 is the one with a connection that has a short circuit.

how to fix a short circuit in a car

How Do You Fix a Short Circuit in a Car?

Once you identify the fuse that has a connection with the short circuit, carefully trace the wire. After that, you can use either of the two methods below.

Tape the Exposed Wire

Once you locate the exposed wire, get a good tape and apply it to form several layers on the bare wire to cover it properly. This will salvage the situation. However, the next option is a better method in this situation.

Cut the exposed wire and install a connector.

If you don’t want to apply the first method, simply cut the exposed wire and install a connector at that point to link both ends of the shorting wire.

After connecting the wire, ensure to use a circuit tester to monitor the circuit as you fix it back in place. Then, test the circuit again as you fix the fuse back in place.

How Can You Prevent a Short Circuit?

Preventing short circuits in your car requires developing a safety check habit. Some of the checks involve the following.

Check for moisture

Water and electricity must not be allowed to meet. This can result in multiple electrical problems in a car. 

So, you must check out moisture around any of the electrical components in your car and clean them up properly. Also, ensure to avoid moisture from getting in contact with your car’s electrical components and the wires.

Regularly wire check

Ensure to perform a regular wire check to identify wear and tear that can lead to a short circuit. It would be best to do this as part of your regular maintenance routine.

Avoid overloading

Overloading is a common cause of short circuits in a car because of the excessive heat it generates. Make sure you avoid plugging too many devices into your car’s electrical components as you drive.

Check devices before connecting.

Ensure to check devices before plugging them into your car. Some devices may have a short circuit present which will most likely affect your car’s electrical components.

FAQs

Q: How much does it cost to fix an electrical short in a car?

Fixing an electrical short in a car costs around $75 – $200. This includes parts and labor costs. However, this car short circuit repair cost is relative to the location of the auto technician performing the task and the location of the auto parts merchant.

An electrical short can hinder the proper functioning of a vehicle’s electrical components, resulting in overheating, fire outbreak, or explosion. This problem can lead to severe damage if not properly rectified after you discover it.

Q: Can you drive a car with an electrical problem?

Driving a car with an electrical problem may be possible but not advisable. Although the vehicle may move irrespective of the fault; however, it may cause severe damage to the car. Some common disasters you may likely experience include overheating, fire, or unexpected explosions.

Risking these damages is not worth it when you can actually contact an expert auto technician to fix the problem immediately. Alternatively, you can tow the vehicle to the technician’s workshop to fix the problem.

Q: What are the effects of short circuit?

Overheating, explosion, or fire outbreaks are some common effects of short circuits in a car. These effects can be very dangerous if you fail to avoid them.

Electrical faults may not alter the proper functioning of some components in a vehicle; however, they can get you stranded in the long run if you fail to fix the fault.

A malfunctioning electrical system can also lead to arc flash, resulting in serious injuries including blindness, deafness, nerve damage, etc. So, if you notice any short circuit in your car, ensure to contact a professional auto technician to fix the problem immediately.

Q: How do you find a short in a wiring harness?

Finding a short in a wiring harness is pretty straightforward. You simply need a multimeter to test the continuity of the various wires that are available.

After that, you can divide the wires into a group of halves until you identify the wires with the short. The multimeter can also be helpful if you’re wondering how to find an open circuit in a car.

Meanwhile, the procedure below will help you find a short in your car’s wiring harness when you need to fix a fault.

  • Get a working multimeter.
  • Set the multimeter on continuity mode.
  • Isolate the various wires on a particular end of the harness.
  • Pack the leftover wires on the other end in two groups.
  • Connect the bare conductor in every group with alligator clips.
  • Clip the multimeter’s black probe lead to one bundle of the wires and clip the red probe lead to the other bundle. It will beep in case there’s a short.
  • Categorize the bundle that beeps into two separate smaller bundles.
  • Test each of the smaller bundles. One will beep.
  • Continue to separate and test the beeping bundles into two until you get the last wire with the short.
  • Do the same with the other bundle until you identify the short wiring.

Q: Can a short circuit damage a battery?

A short circuit cannot damage a car’s battery; however, it may heat up the car’s battery, increase the temperature, and cause the battery to discharge. A short circuit can be risky to manage around.

This malfunction can trigger a car’s engine to overheat and also result in unexpected fire outbreaks. So, if you drive a car with a short circuit, ensure to fix it as soon as possible to avoid any unexpected fire outbreak or explosion.

Final Words

This article has shed light on how to find a short circuit in a car. So, you don’t have to panic when faced with this situation. However, it is important to note some of the common causes of short circuits and how to prevent them.

Meanwhile, if you suspect a short circuit in your car, kindly check the step-by-step procedure on how to fix a short in a car above to determine the short circuit location and fix it as recommended in this guide.

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Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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