Car Electrical Problems Troubleshooting Tips

Unlike a loud engine knock or noisy exhaust, car electrical problems can be harder to diagnose and pinpoint. Many functions in your vehicle require a sound electrical connection that relies on a series of wires, the battery, the alternator, and the vehicle’s computer.

Modern vehicles, in particular, have extremely complex electrical systems, as almost everything the driver interacts with is connected in one way or another to the electrical system.

This article will summarize common vehicle electrical problems and how to troubleshoot them so you can decide how to proceed when it comes time to fix the problem.

Car Problems that Electrical Problems may cause

Vehicle Will Not Start

This is one of the most common electrical problems people encounter with their cars. When you put the key in the ignition, if it is not starting as it should, you probably have a problem with one of three electrical components – the battery, the alternator, or the starter.

Batteries usually do not fail immediately – you will usually see a warning light signaling that it is time for a replacement before they die completely. One warning sign might be a slower turning starter (for instance, the car starts, but it takes longer than usual to turn over).

Keeping the battery terminals clean and free of oxidization is also important to ensure a proper connection to the vehicle’s electrical components. A functioning battery can act as a dead battery if the terminals are corroded. Battery terminal cleaner can be purchased at any auto parts store.

The problem is likely with your battery if the interior lights are on when you open the door, but the car will not start. In such cases, you may hear several clicks when you try to start the vehicle. Conversely, if the interior lights are off and the car won’t start, you probably have a dead battery.

Dashboard Lights Flicker or Dim

If your dashboard lights are flickering or your headlights are dim while driving, this is also a sign of an electrical problem. Depending on the cause, the problem could be with your battery, alternator, or voltage regulator.

The voltage regulator controls how much electrical output the alternator makes. If it fails, it can cause issues with charging and electrical components because the alternator is either putting out too little or too much voltage. If the problem is with the battery, it may be charging slower or having difficulty holding a charge, resulting in the dashboard lights dimming or flickering.

Lights or Brake Lights Not Working

A third common electrical problem with vehicles happens when the headlights or brake lights are not working, but the rest of the car is running fine. This could indicate a problem with one or more of the fuses. The purpose of a fuse is to protect the wiring in a car and not the electrical device that the fuse is connected to. If a fuse is blown, it is more likely that something else is causing the issue. For instance, if you replace the fuse and it blows again, it is most likely shorting out somewhere in the wiring.

How to Fix Car Electrical Problems

In modern vehicles, fixing electrical problems is not always easy, but it can be done with a few basic tools and some basic knowledge. The first tool you’ll need is a multimeter, which measures voltage and resistance. Alternatively, you can use an ohmmeter to measure resistance and a voltmeter to measure voltage, but a multimeter performs both functions.

Keep In Mind
Before disconnecting wires, keep track of the colors of wires and where they connect – it is helpful to take pictures before you start so that you know where wires belong when it comes time to reconnect them.

For every device in your vehicle that requires electrical power, a minimum voltage is necessary for it to operate correctly. To check if a certain device is working as it should, you can measure the voltage at various load points on the car.

Check the Battery
The first step in discovering an electrical problem is to measure the battery’s voltage output using your multimeter or voltmeter. Disconnect the battery from the car and make sure all lights are off. If the key is in the ignition, make sure it is turned to the off position.

Connect the red lead to the positive (RED) battery terminal and the black lead to the negative (BLACK) battery terminal. If the voltage reading is around 12.66V, your battery is fully charged.

If the voltage reading exceeds 12.43V but is less than 12.66V, your battery is about 75%-90% charged and is still operable. If the voltage reads less than 12.4V, the voltage output is too low, and the battery needs to be charged. One option is to jump-start it with another vehicle using jumper cables.

If you choose this option, it is best to go for a 20 to 30-minute drive (instead of a series of short trips) after getting it started to ensure the battery gets fully charged. If the battery is four years old or older, it may be time to replace it. Some batteries last longer than others, but as a general rule, most car batteries last about four years.

Check the Alternator
The problem could be with the alternator if the battery voltage levels seem normal. Testing the alternator assumes you can start the car. If the battery levels are normal, you should be able to start the engine.

Next, using the leads on your voltmeter (or multimeter), connect the red lead to the positive (RED) terminal connector on the alternator. Connect the black lead to some metal part of the car for a ground connection.

Make sure your voltmeter is set to the 20V setting. If the alternator operates properly, the voltage should be around 14 volts. Sometimes, the reading will be slightly under that value and sometimes slightly over that value. Values between 13.8 and 14.2 are good.

If the voltage reading is excessively high, it could be that the voltage regulator is failing. If the reading is lower than normal, the problem could be several different things. Try revving the engine to about 2000 RPMs and see if the reading changes. If the voltage is normal when revving it, your alternator is good.

If the voltage is still too low even with revving it, the alternator probably needs replacing.

Checking Load Points Voltage and Ground Connection
To check whether or not a particular device is working properly, check its load points using the leads on your multimeter. You can also check your ground connection this same way. If the voltage is zero at these points, the fuse that protects that device must be replaced.

Remember not to replace an existing fuse with one that has a higher current rating, as the wires are not designed to carry that much current. If a fuse does continue to blow, then the most likely causes are:

• A failed electrical component. (like a motor or electronic device)
• A wire that has had its insulation compromised and is grounding out.

Corroded Wires or Damaged Wiring Harness
Wires can wear out over time due to extreme driving or weather conditions. Look for wires that are corroded or disconnected. It may be hard to tell which wires are damaged, but you can test the voltage using a multimeter tool. If there is a voltage drop of more than 0.1V along two points of the wire, it needs to be replaced.

Another common electrical problem is a damaged wiring harness. Wiring harnesses are collections of wires that supply power to the engine, transmission, or other vehicle components. Some are encased in insulation, which can deteriorate, exposing the wires underneath and causing some devices to short out. In this case, replacing the wiring harness should solve the problem.

Regularly checking the electrical systems in your vehicle is important to keep it running smoothly. We hope you found this guide helpful. For more troubleshooting tips, check out our other troubleshooting and repair guides.

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