Troubleshooting a Vehicle Electrical System

Your Vehicle's Electrical System

Your vehicle requires electricity to run, and this applies to all vehicles, not just hybrid electric vehicles. That internal combustion engine under the hood depends on electricity to get it started and to keep it running, while the on-board, sophisticated computers, navigation, communication, and entertainment systems require a steady flow of electricity to function properly. Generating, storing and distributing all that power reliably and consistently falls to the vehicle’s electrical system, the heart of which includes the battery, alternator and starter. When any one of these three aren’t functioning properly, problems are sure to arise.

Test these electrical system parts

old battery


A vehicle battery doesn’t last forever—generally three to five years. Look for stickers on top of the battery that indicate the month and year the battery was manufactured or installed. Detailed battery performance intel can be obtained via a diagnostic test using a hand-held battery tester. The results can reveal the battery's condition and indicate whether it's approaching the end of its life.

Pro Tip

Have the battery tested first to eliminate it as the source of electrical system problems.



A grinding or clicking sound from under the hood when turning the key, or the need to turn the key several times before the engine turns over could indicate a looming starter failure. Unfortunately there really aren't any guidelines indicating how long a starter will last, nor is there preventive maintenance for a starter. In the best-case scenario, you'll notice the starter beginning to fail and have it replaced before it fails completely. If it's time to perform this repair, learn how to replace a car starter.




Transforms mechanical energy into electrical energy and works with the battery to supply power wherever it’s needed, including continuously recharging the battery. If the alternator stops working, the vehicle will continue to run for a short time until the battery’s power is depleted. Warning signs associated with a failing alternator can include a dead battery, lights that are noticeably dimmer, difficulty starting, and illumination of the dashboard battery light. Testing the electrical system with a voltmeter will provide insight into the alternator's condition. Here is our alternator installation guide.

If you're not comfortable testing an alternator or testing a starter, it's a simple job that your local mechanic can do, or you can have the check performed at Advance. Whether the battery, starter, or alternator is the source of your vehicle's electrical system woes, the solution is the same—replace the malfunctioning part with a new one.

Free Testing at Advance

Stop by your local Advance Auto Parts store to take advantage of our free starter, alternator and battery testing. If your battery is failing, and it's time to purchase a new battery, we offer free installation*. 

*Car battery testing and installation available on most automotive vehicles, at most locations, unless prohibited by law.

Last updated March 18, 2021