How To Check Car Alternator With Multimeter. To check for a possible bad alternator diode switch your voltmeter to a low setting on the AC alternating current voltage scale. Your voltmeter should read 0 AC volts.
If you dont have one lying around you can evaluate the state of the alternator without a multimeter. Make sure your alternators positive and negative terminals are clean. Simply check the voltage of your battery by touching the multimeter prongs to the terminals with the car shut off.
How to Test Car Alternator with Multimeter.
If you just got a brand new battery and your car is not starting then you definitely have a faulty alternator on your hands. OK the test is divided into three parts. Car batteries have a resting voltage somewhere between 1245 and 126 volts in most cases. Turn off your engine and grab the multimeter.
