Armature
- Verify that there is no continuity between the commutator and the core at each segment using an ohmmeter. If there is continuity, replace the armature. (Scheme 10)
- Verify that there is no continuity between the commutator and the shaft using an ohmmeter. If there is continuity, replace the armature. (Scheme 11)
- Place the armature on V-blocks, and measure the runout using a dial indicator. If not within the specification of, runout 0.002" (0.05 mm) maximum, repair using a lathe or replace the armature. (Scheme 12)
- Measure the commutator diameter. If not within the minimum specification, standard commutator diameter 1.16" (29.4 mm), minimum commutator diameter 1.13" (28.8 mm), replace the armature. (Scheme 13)
- Measure the segment groove depth of commutator. If not within the minimum specification, undercut the grooves to the standard depth. Standard depth is 0.016-0.023" (0.4-0.6 mm), minimum depth 0.008" (0.2 mm). (Scheme 14)
Scheme 10
Scheme 11
Scheme 12
Scheme 13
Scheme 14
Magnetic Switch
- Inspect for continuity between terminals (S) and (M) using an ohmmeter. If there is no continuity, replace the magnetic switch. (Scheme 15)
- Inspect for continuity between terminal (S) and the body using an ohmmeter. If there is no continuity, replace the magnetic switch. (Scheme 16)
- Verify that there is no continuity between terminals (M) and (B) using an ohmmeter. If there is continuity, replace the magnetic switch. (Scheme 17)
Scheme 15
Scheme 16
Scheme 17
Brush & Brush Holder
- Verify that there is no continuity between each insulated brush and the plate using an ohmmeter. If there is continuity, replace the brush holder. (Scheme 18)
- Measure the brush length. If any brush is worn almost to or beyond the minimum specification, replace all the brushes. Standard brush length for automatic transmissions is 0.69" (17.5 mm), for manual transmissions it is 0.48" (12.3 mm). The minimum brush length for automatic transmissions is 0.47" (12.0 mm), for manual transmissions it is 0.28" (7.0 mm). (Scheme 19)
- Measure the brush spring force using a spring balance. If not within the minimum specification, replace the brush spring. Standard spring force for automatic transmissions is 5.24-7.12 ft. lbs. (23.3-31.7 N.m), for manual transmissions it is 4.12-5.59 ft. lbs. (18.3-24.9 N.m). The minimum spring force for automatic transmissions is 2.25 ft. lbs. (10.0 N.m), for manual transmissions it is 1.3 ft. lbs. (5.9 N.m). (Scheme 20)
