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Bench Testing: Rotor

  1. Place ohmmeter on lowest scale. Connect ohmmeter across slip rings. For resistance values, see ROTOR RESISTANCE  table.
    ROTOR RESISTANCE

    Alternator Ohms
    90-amp 2.6 - 3.2
    115-amp 2.4 - 2.9
  2. If resistance is too low, rotor has short circuit and must be replaced. If resistance is infinity (no continuity), rotor has open circuit and must be replaced.
  3. Place ohmmeter on x1000 scale. Connect ohmmeter between either slip ring and rotor core. No continuity should exist. If continuity exists, rotor is grounded and must be replaced.
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