Troubleshooting Car Electrical Problems

Jean Scheid
Use the Right Cable!

Before you consider troubleshooting car electrical problems on your own, be sure you know about basic electric circuits. If you don't, it's best to take your car to a qualified mechanic.

Tips On Troubleshooting Car Electrical Problems

LTK Cars spoke to Automotive Service Excellence (ASE) certified technician Eric Stanerson of Enchantment Ford in New Mexico about car electrical problems. According to Mr. Stanerson, "Unless you're knowledgeable about a car's electrical components, there are only two elements of the basic twelve-volt electrical engine you should test on your own; the battery and the alternator." Other components require test lights along with other mechanical diagnostic tools that you may not have handy or know how to use. Mr. Stanerson does recommend purchasing a voltmeter from a local parts store to help test both your battery and alternator.

The Battery

The purpose of the battery is to store electrical energy in a chemical form. The battery sends current to help start or crank the engine. Mr. Stanerson tells LTK Cars that, "Many problems starting the engine are due to battery problems." Take a look at your battery first and find the positive and negative cables. The positive or "+" sign has a red cable. The negative or "-" sign has a two-wire black cable. The positive cable is connected to a junction block, while the negative cable is connected to what is called the accessory ground.

The Alternator

The alternator in your car's engine charges voltage to help electrically power your car. It also helps to recharge the battery, but only when the engine is running. "If some of your car's accessories such as the radio or lights aren't working, those are usually due to a problem with the alternator," Mr. Stanerson said. "If you follow the junction box from the positive (red) battery cable, you'll find the alternator, which also has a red cable running from the back of it." The alternator also has a belt that turns when your engine is running.

Testing the Battery and the Alternator

To see if your battery is charged and working at the proper voltage level, use your voltmeter and connect the red wire lead from the voltmeter to the red or positive battery cable. Next, connect the black wire lead from the voltmeter to the black or negative battery cable. To be safe, do this when your vehicle is not running and wear protective clothing and gloves to protect yourself from shock or battery explosion. If you get a read of between 12.5 and 12.8 volts, your battery is most likely fine.

Using your voltmeter to check your alternator is easy as well if you're careful. Take your voltmeter's red wire lead and connect it to the alternator's red cable. The voltmeter's black cable should be connected to some sort of ground. A good ground is a nut or bolt that is unpainted and free of dirt. "Find a bolt or nut that is on the frame or outline of the car's engine," Mr. Stanerson recommends. Next, you will have to start your engine and read the voltmeter. If you get a reading of 13.6 to 14.3 volts, your alternator is in good shape.

Tips on Testing

For more information on troubleshooting car electrical problems, one great website is Imperial Web Pages. This site offers good diagrams of the electrical system as well as useful tips on how to easily check your vehicle's voltage in the battery or alternator.

When testing, always remove any jewelry or clothing that could get stuck in the engine or other moving parts. If you feel wary about using a voltmeter or testing any electrical element, stay on the right side of safety and visit a qualified technician or your auto repair center.

"With all the technology in today's engines, troubleshooting car electrical problems is more difficult than most people realize," offers Mr. Stanerson.

Troubleshooting Car Electrical Problems