Field Open Or Short Circuit Test

Set ohmmeter on "x1" scale. Contact one probe to alternator FLD terminal and connect other probe to GND terminal. See Figure . Spin alternator pulley. Ohmmeter should read between 2.4-100 ohms and should fluctuate while pulley is spinning. An infinite reading indicates grounded brush lead, worn or stuck brushes or bad rotor assembly. A reading of less than 2.4 ohms indicates grounded brush assembly, grounded field terminal or a bad rotor.