On the previous page, you learned that dim exterior and interior lights are common symptoms of alternator trouble. If your lights aren't actually dim, they might be flickering instead. These two symptoms often go hand in hand, but not always. If your lights are bright, then dull, then bright again (either on a regular beat or seemingly at random) then you definitely have a problem with your electrical system, and the alternator is the most likely culprit. The reasoning is the same as if the lights were simply dim — the alternator just isn't generating enough juice to keep the lights going at full strength, and instead of dimming all of the lights in response, your car is trying, and failing, to maintain the proper lighting output.
If you want to be sure that the problem is the alternator, rather than something else in the electrical system, simply look for a pattern. Can you pinpoint that the lights flicker when you do something else that draws electricity, such as turning on the radio, adjusting the climate control or using your power windows? That will be the key to helping you narrow down the possibilities, since it demonstrates your lights are flickering in response to the extra load on the system. As you continue to read through this article, you'll see that a failing alternator simply can't keep up with all of the things you ask your car to do during a typical drive.