Field Coil Shorted

Place alternator on an insulated surface. Connect ohmmeter between snap rings. Reading should be 1.5-2.0 ohms. A reading of 2.5-3.0 ohms indicates field coils have been operated at higher than normal engine compartment temperatures.

Readings above 3.5 ohms indicate high resistance, requiring further testing or replacement. If reading is below 1.5 ohms, field coil is shorted.