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While the engin is running remove the negative side of the battery. If your car dies, your alternator is probably bad...

Of it it wasn't when you started, there's a good chance it is now.

NEVER disconnect the battery or alternator while the engine is running. You can fry alternator diodes, computers in the car, electronics you have installed, pretty much any sensitive electronics can be damaged or destroyed.

Take your car to get it checked. Most autoparts stores these days will do free alternator tests.

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Q: How do you test for a bad alternator?
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Related questions

How do you wire alternator to a battery to test alternator?

run it and then disconnect the negative wire from the battery if alternator dies its bad.


How do you know if your alternator is bad?

If it is makeing a noise or is not putting out at least 13.5 volts it is bad. Take the car or the alternator to an Auto Parts store and have them load test the alternator to be sure.


What could be the problem when a 1981 Chevy Corvette does not charge?

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What can cause a battery light to come on when the battery and alternator both test good on a 1992 SC 400?

Battery light usually means alternator not charging. Most common solutions would be be a bad alternator, bad connection, or loose alternator belt. If the battery and alt test ok than check the connections to the alternator and battery.


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To test the alternator if funds are low, let the motor idle and remove the negative battery cable, if the motor dies its probably the alternator.


How do you tell alternator is bad?

The best way is to drive it to your nearest auto parts store and have it tested. You can test it somewhat yourself. Start the engine and use a volt meter to test the voltage that is being supplied by the alternator for the battery. If it is less than 13.5 volts the alternator is bad.


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Will a diesel engine run with battery cable disconnected if the alternator is bad?

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How do you know when alternator is bad?

Typically you know your alternator is out when you have to jump start your car numerous times. A way you can test it is by turning on your car and while it's running discount the + terminal. If the car turns off then your alternator is bad. If the car remains in then alternator is good and possible bad battery. Hope this helps


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