Fuel may power your car, but its electrical system does much of the heavy lifting to keep you motoring. And when problems arise with these components, it can be costly.
Fortunately, if you can spot electrical issues from the start and have a little insight to make a diagnosis, you might be able to save yourself from a huge bill at the auto shop. To keep your ride powered strong here are three common auto electrical issues and how to troubleshoot them with the help of a digital voltmeter.
Engine Doesn’t Start
A car’s battery gives the engine the initial charge it needs to process fuel and move the car forward. If the engine isn’t turning over when you engage the ignition, the battery may not be delivering sufficient voltage. Other signs of low voltage include dim headlights, frequent need for jumpstarts, and a battery warning light on the dashboard.
To diagnose the problem, use a digital voltmeter to measure the battery’s voltage. Often referred to as a multimeter, this device features electrical leads that can be placed aside the battery terminals to measure electrical output.
With the engine off, the voltmeter should read about 12.6 volts. With the engine on, it should be at least over 10 volts.
If your readings are below these levels, first try cleaning the battery terminals and reconnecting the cables. In some cases, built-up corrosion may be blocking the flow of electricity, resulting in low-voltage issues.
If the cable connections appear clean, your next best bet is to charge the battery to see if that increases the voltage output to appropriate levels.
Replace the battery if these solutions don’t improve the voltage.
If a new battery continues to put out low voltage, visit an auto shop to see if the alternator is the source of the problem. Among other electrical issues, a faulty alternator won’t be able to recharge the car battery so that it delivers consistent voltage between trips.
Malfunctioning Radio, Turn Signal, Windows, or Other Electrical Components
When a car starts reliably but other minor electrical issues surface, a fuse may be blown. A blown fuse can cause a variety of annoying problems—such as not being able to use your car’s turn signal, radio, interior lights, climate control system, or power windows.
Fuses are often located beneath the steering wheel or under the hood, but you can refer to your vehicle owner’s manual to learn how to access them. Your manual should also provide a guide that maps out which fuses connect to specific features—such as radio or interior lights.
The easiest way to test for a blown fuse is to use a digital voltmeter. First, set your voltmeter to measure direct current (DC). Next, turn the ignition ON but keep the engine off. Finally, connect a voltmeter lead to the metal pins that protrude from the top of the fuse. In some cases, you’ll need to measure each pin’s voltage separately.
If each pin puts out 12 volts, the fuse should be good. If either pin puts out less than 12 volts, then it’s blown and needs to be replaced. Fortunately, fuses are relatively cheap to replace without the help of a mechanic.
Poor Acceleration or Decreased Fuel Economy
Spark plugs ignite the air/fuel mixture in the engine at the right time to provide the perfect balance. If a spark plug is bad, this imbalanced mixture can lead to a variety of problems including reduced acceleration, engine misfires, and poor fuel economy.
Spark plugs are located at the top of the engine’s cylinder heads. There should be a spark plug for each cylinder. So, if you have a four-cylinder engine, you would have four spark plugs to check.
Just as with a bad battery or blown fuse, a faulty spark plug can be detected with a digital voltmeter.
If you want to test a spark plug, first cut the fuel supply to the engine. This is usually done by removing the fuse for the fuel pump and powering the engine until lingering fuel is burned off.
Next, follow your owner’s manual instructions on how to remove the spark plug from the cylinder. Typically, you’ll need to separate it from an attached coil pack and then pull it from the cylinder head.
Once removed, set your digital voltmeter to read Ohms. Next, touch the voltmeter’s leads to each end of the plug. Depending on the model, a spark plug should produce between 4000 and 8000 Ohms. Any reading below this range would mean that the plug needs to be replaced. Even if you can’t fix an auto electrical issue by testing and replacing a faulty part, don’t wait to take action. Waiting too long may cause the problem to worsen and cause the electrical component to fail. Using the information provided by inexpensive diagnostic tools—such as a multimeter—you’ll get to the root of the problem more quickly and have the insight necessary to consult with a mechanic.