Why Is There an ALT Light on My Dashboard?

The ALT light on your dashboard is for the alternator. If you don’t have an ALT light, you may have a GEN light or a battery-shaped light. If any of these lights come on at any time other than when you first start your automobile, this is a sign that your alternator is going bad. This is just one sign. Hummel’s Automotive Diagnostic & Repair is going to list the other signs below.

Dim Headlights

You know your vehicle has an electrical problem if the headlights are dim. They may also go from being overly bright to dim. Any time your headlights are not illuminated normally, this can be a sign that there is a problem with the alternator. You may also have problems with your taillights and interior lights.

Dead Battery

You will end up with a dead battery if the alternator has died. This is because the alternator powers the battery. Your battery cannot hold the charge if the alternator isn’t sending voltage to it. Consequently, even if you jump-start the battery, it will die again.

Malfunctioning Accessories

The alternator provides power to your vehicle’s accessories. This includes the entertainment system, the GPS, and the power seats and windows. If any of the accessories malfunction or slow down, it’s possible that their power supply is compromised by a malfunctioning alternator.

Hard Starting

If your alternator is still providing some power to the battery, you may be able to get your automobile started but it will be difficult. Your engine may crank several times before it fires up. This is a sign that the alternator is going bad or that it’s time to replace your battery.

Frequent Stalling

Aside from powering your vehicle’s accessories, the alternator also powers the spark plugs. Consequently, if the alternator is unable to provide power to the spark plugs, your engine will misfire and stall. In fact, it will stall frequently.


The alternator or the alternator belt may let you know that there is a problem by making noise. If it’s the alternator that is making noise, this will sound like grinding or growling coming from the engine. If it’s the alternator belt, it will be a whining sound.

Look no further than Hummel’s Automotive Diagnostic & Repair in St. George, UT, for all of your automotive service needs including the alternator. If you are experiencing any of the symptoms listed above, call our shop to schedule a service appointment. We’ll get to the bottom of the problem and fix it.

Photo by Baloncici from Getty Images via Canva Pro

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