GMC 1989 Light Duty Truck, Repair Manual, Page: 663 / 998

SP (MT) STARTING MOTORS 6P3-3
ings, bent arm ature shaft or loose pole shoes
allowing the arm ature to drag.
b. S h o rte d a r m a tu r e . T h is ca n be fu r th e r
checked on a growler after disassem bly.
c. Grounded arm ature or fields. Check further
after disassem bly.
3. Failure to operate with high current draw indicates:
a. A direct ground in the term inal or fields.
b. Seized bearings. This should have been noted
by turning the arm ature by hand.
4. Failure to operate with no current draw indicates:
a.
Open field circuit.
This can be checked after
disassem bly by inspecting internal connections
and tracing the circuit with a test lamp.
b. Open arm ature coils. Inspect the com m utator
for badly burned bars after disassembly.
c. Broken brush springs, worn brushes. High
insulation betw een the com m utator bars or
other causes which would prevent good contact
between the brushes and com m utator.
5. Low no-load speed and low current draw indicates a
higher internal resistance due to poor connections,
defective leads, dirty com m utator and causes listed
under step 4.
6. High free speed and high cu rren t draw indicates
shorted fields. If shorted fields are suspected, replace
the field coil assem bly and check for improved per­
formance.
DISASSEMBLY
If the motor does not perform to specifications, it may
need to be disassem bled for further testing of the com po­
nents. Normally the starting m otor should be disassem bled
only so far as is necessary to make repair or replacem ent of
parts. As a precaution, it is suggested that safety glasses
be worn when disassem bling or assem bling the starting
motor.
FIELD FRAME
*
Disassemble (Figures 4 and 5)
• Clean the outside of the starter housing, removing
grease, oil, mud, etc.
• Make scribe marks to show the relationship of the
nose housing, lever housing, field fram e, and end
fram e to aid in assembly.
1. Field coil strap (51) from the solenoid m otor term inal
(figure 6).
2. Through bolts (35).
3. End fram e (41).
4. W asher (34) from the com m utator end of the arm a­
ture shaft (SD-300).
5. Field fram e (41) from the drive housing (31) and the
arm ature assem bly (9).
6. Arm ature from the drive housing by tilting the arm a­
ture to disengage the shift lever fingers (1) from the
drive collar (32) (figure 7).
1. S h ift Lever
2. P lu n g e r
3. S o le n o id
5. S p rin g
9. A rm a tu re A s s e m b ly
11. G ro m m e t
31. H o u s in g
32. Drive
33. B ru sh
34. W a s h e r
35. B o lt
36. S cre w
37. R ing
38. H o ld e r
39. C o lla r
40. Pin
41. F ram e
42. B ru s h e s and H o ld e rs
43. S h a ft
F-04211
F ig u re 4 — S D -2 0 0 (5 M T ) C o m p o n e n ts