Starting/Charging Systems (H4SO): Starter: Inspection: Armature

1. Check the commutator for any sign of burns of rough surfaces or stepped wear. If wear is of a minor nature, correct it by using sand paper (#300).
2. Run-out test

   Check the commutator for run-out, and then replace if it exceeds the limit.

   Commutator run-out: 

   Standard 

   3.1 mm (0.1220 in)

   Service limit 

   Less than 3.8 mm (0.1496 in) 

   Fig 1: Checking Commutator For Run-Out

   Courtesy of SUBARU OF AMERICA, INC.
3. Armature short-circuit test

   Check the armature for short-circuit by placing it on growler tester. Hold an iron sheet (thickness gauge, etc.) against the armature core while slowly rotating the 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.

   Fig 2: Checking Armature For Short-Circuit

   Courtesy of SUBARU OF AMERICA, INC.
4. Armature discontinuity test

Using a circuit tester, touch one probe to the Armature and the other to commutator. There should be no continuity. If there is continuity, the armature is grounded.

Replace the armature if it is grounded.

Fig 3: Identifying Armature Discontinuity Test

Courtesy of SUBARU OF AMERICA, INC.