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Bench Testing: Armature

WARNING: This page is about a different car, the 2004 Subaru Forester, 2003 Subaru Forester, and 2002 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check commutator for any sign of burns of rough surfaces or stepped wear. If wear is of a minor nature, correct it by using sandpaper.
  2. Check the commutator run-out and replace if it exceeds the limit. See Fig 1 . See STARTER SPECIFICATIONS  table under STARTER SPECIFICATIONS.
  3. Check the depth of segment mold. See Fig 2 . See STARTER SPECIFICATIONS  table under STARTER SPECIFICATIONS.
  4. Check armature for short-circuit by placing it on growler tester. See Fig 3 . Hold a iron sheet against armature core while slowly rotating armature. A short-circuited armature will cause the iron sheet to vibrate and to be attracted to core. If the iron sheet is attracted or vibrates, the armature, which is short-circuited, must be replaced or repaired.
  5. Using a circuit tester, touch one probe to the commutator segment and the other to shaft. See Fig 4 . If there is no continuity, it is normal. If there is continuity armature is grounded. Replace armature if it is grounded.
Fig 1: Testing Commutator Run-Out
G00214940Courtesy of SUBARU OF AMERICA, INC.
Fig 2: Testing Segment Mold Depth
G00214941Courtesy of SUBARU OF AMERICA, INC.
Fig 3: Testing Armature
G00214942Courtesy of SUBARU OF AMERICA, INC.
Fig 4: Testing Armature's Grounding
G00214943Courtesy of SUBARU OF AMERICA, INC.