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Diode Checks

  1. Connect leads of an ohmmeter to terminal 30 and stator winding connector. Check resistance, then reverse leads and recheck. Both readings should show high resistance with one reading being slightly higher than the other. If both readings are low, a positive diode is bad.
  2. Check resistance between ground and stator winding connector. Reverse leads and check reading. If both readings are low, a negative diode is bad.
  3. Check resistance between energizing diode plug and stator winding connector. Reverse leads and check reading. If both readings are low, an energizing diode is bad.
    Fig 1: Marelli Alternator Test Points
    G09334913Courtesy of NOT AVAILABLE