Armature Test
- Check armature for short using a growler and hacksaw blade. Hold hacksaw blade against armature while slowly rotating armature in growler. A shorted armature will cause hacksaw blade to vibrate and be attracted to armature core when passed over shorted area. Replace armature as necessary.
- Use an ohmmeter to check for grounded armature. Touch one probe to each segment of commutator and hold other probe to armature core. If continuity exists, replace armature.
- Use ohmmeter to check commutator for open circuit. If continuity does not exist between any 2 commutator segments, replace armature. Check commutator for outside diameter wear, runout and mica insulation depth. See STARTER SPECIFICATIONS .
- If correcting runout condition, DO NOT reduce commutator diameter below specification. Undercut mica insulation if it is even with or higher than commutator surface. See Fig 1. See STARTER SPECIFICATIONS .
Courtesy of SUBARU OF AMERICA, INC.