ALTERNATOR WARNING LIGHT
ALTERNATOR WARNING LIGHT "What does that little red light that says ALT mean when it comes on?" Very basically, it means that either the alternator output voltage is lower than the battery voltage, or the battery voltage is lower than the alternator output voltage. If the light gets dimmer as you rev up the engine, then you most likely have a problem with the alternator. If it gets brighter, then the battery is most likely bad. CLICK HERE That's all well and good, but just exactly what does all that mean? To get a good idea, it is first necessary to understand how an alternator works. You don't need an engineering degree, just a basic understanding of the general principles. Figure 1, below, is a block diagram, or a "functional" diagram, of an alternator, and its connections to the remainder of the automobile electrical system. Following the figure is a description of ...
