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Q: Battery light is on, car didn't crank, took power post off battery and car shut off does this mean I need a new alternator??

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Car battery light is on headlights and inside lights are dim took power post off battery and car shut off does this mean I need a new alternator??

My car has 157000 miles.
My car has an automatic transmission.

You should never disconnect a cars battery while the engine is running or you may cause a voltage surge that can burn out the computers and modules/components in the car causing more problems. This is a test that was done on cars before they were computer controlled. Your battery light needs to have the battery and charging system checked to see if the alternator needs replaced. You will also want to check the main cable from the alternator to the main fuse power panel to make sure the wiring is not shorted anywhere in between.

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