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. 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.