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Rotor Test

  1. Using an ohmmeter, check for continuity between rotor and slip rings. Perform STEP 1. See Fig 1 . If continuity exists, replace rotor.
  2. Check continuity between slip rings. Perform STEP 2. See Fig 1 . If continuity does not exist and resistance is not 2.8-3.0 ohms, replace rotor.
  3. Measure diameter of both slip rings. If either slip ring diameter is less than .504" (12.8 mm), replace rotor. If slip rings are scored or rough, replace rotor.
Fig 1: Testing Generator Rotor
G91H02012Courtesy of GENERAL MOTORS CORP.