Pull Battery Cable To Test Alternator

If it decreases and starts to drop until vehicle eventually dies you have a defective alternator.

Pull battery cable to test alternator.

Pcm tcm electronic power steering radio etc. In the pre computer days you could pull it off without damaging anything. What are your thoughts. Can you test an alternator by removing battery cable.

Start vehicle and voltage on voltmeter should increase to around 13 volts and stabilize there. But it s no longer a safe test to perform on a modern vehicle. Connect it to the battery and it should read a little above 12 volts when its off and 13. Doing this would allow you to check whether the alternator is putting out enough current to run the vehicle.

Today you risk frying every electrical device in your vehicle. Use a volt meter to test the voltage. Community answer test alternator by connecting voltmeter on dc 20 red on positive battery terminal and black on negative battery terminal. Some newer cars will turn off even if the alternator is working good.

Technically yes but that test can also wind up destroying all the electronics in your car. To do a quick check on an alternator i was told that you could start the car and then remove the negative battery cable. Testing alternator by removing battery cable was a valid test back in the day before computers.