GMC 1989 Light Duty Truck, Repair Manual, Page: 666 / 998

6P3-6 SD (MT) STARTING MOTORS
64
33. B ru sh
49. G ro u n d e d B ru sh H o ld e r
50. In s u la te d B ru sh H o ld e r
63. P ivo t Pin
64. B ru sh H o ld e r S p rin g
65. B ru sh H o ld e r S u p p o rt
F-04219
Figure 9— Driving the Stop Collar Off the
Retaining Ring
62
41 \
33. B ru sh
38. B ru sh H o ld e r
41. F ield Fram e A s s e m b ly
61. Rivet
62. B rush S u p p o rt
A. R oute W ire A s S h o w n
F-04218
F ig u re 10— R eplacin g B rushes on th e S D -2 0 0 (5M T)
Figure 11— Replacing Brushes on the SD-300 (10MT)
4. C om m utator for run out.
— Do not turn the com m utator.
— Do not undercut the insulation.
— Clean the com m utator with No.240 grit emery
cloth. If the com m utator cannot be cleaned,
replace the armature.
5. Arm ature for short circuits (figure 13).
• Rotate the arm ature in a growler with a steel
strip, such as a hacksaw blade, held on the
arm ature parallel to the shaft. The steel strip will
vibrate on the area of the short circuit.
• Shorts between the com m utator bars are som e­
tim es produced by brush dust or copper dust.
6. Arm ature for opens.
• Look for loose connections where the conduc­
tors join the com m utator bars.Poor connections
cause arcing and burning of the com m utator. If
the bars are not badly burned, the leads can be
resoldered.
7. Arm ature for grounds by using a test lamp (figure 14).
• If the test lamp lights when one test prod is
placed on the com m utator and the other test
prod is placed on the arm ature core or shaft, the
arm ature is grounded.
8. Motor housing and solenoid housing for oil and water.
• If oil or water is present, this indicates broken O-
rings, leaking gaskets, or oil seal wear. Replace
all seals and gaskets as required.
9. Brushes for wear.If the brushes are worn to half the
size of a new brush, replace the brushes.