Component Tests and General Diagnostics

Solenoid




1. Check for continuity between S and M terminals with ohmmeter. Replace solenoid if there is no continuity.




2. Check for continuity between S terminal and solenoid body with ohmmeter. Replace solenoid if there is no continuity.




3. Check continuity between M and B terminals with ohmmeter. Replace solenoid if there is continuity.

Brush and brush holder




1. Check continuity between each insulated brush and plate with ohmmeter. Replace brush holder if there is continuity.
2. Measure the force of brush spring with spring balance.

Brush spring force: 2.0 lb (8.8 N)




3. Replace spring if force is insufficient.

Brush




1. If brush is worn to the wear limit, replace all brushes.

Field coil




1. Check for continuity between M terminal wire and brushes with ohmmeter. Replace yoke assembly if there is no continuity.
2. Check continuity between M terminal wire and yoke with ohmmeter. Replace yoke assembly if there is continuity.




3. Check if field coil is loose. Replace yoke assembly if necessary.

Armature




1. Check continuity between commutator and core with ohmmeter. Replace armature if there is continuity.




2. Check continuity between commutator and shaft with ohmmeter. Replace armature if there is continuity.




3. Place armature on V-blocks, and measure runout with a dial indicator.
If runout is not within specification, repair armature with a lathe or replace armature.
4. Replace armature if diameter of commutator is at, or less than, grind limit.

Grind limit:
1.22 in (31 mm)




5. If commutator surface is dirty, wipe it with a cloth; if it is rough, repair it with a lathe or fine sandpaper.




6. Replace armature if depth of mold between segments is at, or less than, minimum.

Depth: 0.02-0.03 in (0.5-0.8 mm)
Minimum: 0.008 in (0.2 mm)