Batter Light ON – Is it a Blown Fuse?

Your car battery warning light – a sign that there is a problem with the car charging electrical system can come on because of various reasons.

Can a popped car fuse cause the car battery light to come on?

Read on to find out if a blown fuse can cause the car battery light to come on, what signs to look out for, and what fuses are likely to be faulty.

Can a Fuse Cause the Battery Light to Come On?

Yes, a blown fuse can trigger the battery warning light to come on if it affects the car’s charging system for example if the alternator is not able to charge the battery.

How a Fuse Can Stop a Battery from Charging?

The alternator is the primary source of power for the car’s electrical system including supplying power to charge the battery.

If the alternator fuse is blown then no power will flow to keep the battery topped up and it will eventually be drained flat by the connected electrical accessories.

Signs that the alternator fuse has blown

The battery warning light will stay ON if you’re driving. You may also experience the dashboard lights dimming and the engine eventually stopping as the battery charge runs out.

Note: These signs may also be caused by a bad battery, loose or corroded wire connections, damaged alternator, belt or a faulty alternator.

So, seeing the above signs is not necessarily confirm that the car fuse has blown.

What Can Cause an Alternator Fuse to Blow?

The alternator fuses are designed to handle large currents usually over 100 A. So if it blows then there’s likely a short circuit in the wiring. Check the following:

#1. Have you added any electrical accessories or wiring? For instance, replaced a battery or alternator?

A loosely fitted cable as can happen when fitting a new battery or alternator can ground out the alternator output causing the fuse to blow.

#2. An alternator fuse will pop if there is a short circuit in the connected wiring. Consult your car’s electrical wiring diagram – Are there sensors and or any other electrical equipment that is connected to the alternator output via the fuse?

A short circuit in any of them will pop the fuse.

In some cars depending on the car make and model, the alternator fuse can blow when there was a short-circuit in the oxygen sensor connecting wires from damaged insulation.

#3. An accidental short of the alternator positive wire can also cause the fuse to blow. This can happen if the battery cables are not disconnected when removing and disconnecting the alternator cables.

Always disconnect the battery wires first before removing the alternator cables to avoid accidentally grounding the alternator output.

#4. A faulty alternator with an internal short to the ground or if not properly connected can also blow the fuse.

Is the copper stud for the positive cable accidentally connecting to the ground?

Final thoughts

Yes, an alternator fuse can cause the battery light to stay On.

If your alternator fuse has blown then you should check if there is loosely fitted wiring, shorting sensor, or other electrical equipment connected to the alternator output or a faulty alternator.

Hope this helps!

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