Stator Test

For 12SI series alternator, measure resistance between stator leads. See Fig 1. If reading is not infinity, replace stator.
On all models, connect ohmmeter leads to any stator lead and to stator frame. Ohmmeter reading should be infinity. See Fig 1.

NOTE: Delco 17SI alternator has delta stator windings and cannot be checked for open circuit.

Fig 1: Testing Stator for Open or Grounded Circuits

Courtesy of GENERAL MOTORS CORP.