Pull Battery Cable To Test Alternator

Connect it to the battery and it should read a little above 12 volts when its off and 13.

Pull battery cable to test alternator.

If it decreases and starts to drop until vehicle eventually dies you have a defective alternator. But it s no longer a safe test to perform on a modern vehicle. If you re tempted to test an alternator by disconnecting the negative battery cable don t do it. Use a volt meter to test the voltage.

Testing alternator by removing battery cable was a valid test back in the day before computers. Today you risk frying every electrical device in your vehicle. Community answer test alternator by connecting voltmeter on dc 20 red on positive battery terminal and black on negative battery terminal. Can you test an alternator by removing battery cable.

In the pre computer days you could pull it off without damaging anything. What are your thoughts. Start vehicle and voltage on voltmeter should increase to around 13 volts and stabilize there. A good alternator may indeed keep the engine running without the negative cable but this was never a good test.

Technically yes but that test can also wind up destroying all the electronics in your car. Pcm tcm electronic power steering radio etc. To do a quick check on an alternator i was told that you could start the car and then remove the negative battery cable.