GMC 1976 ZEO 6083 Maintenance Manual page 445

Figure 72-Shift Lever Removal
housing . Shaft should fit snugly in the bushing. If the
bushing is worn, it should be replaced .
5. Inspect armature commutator . If commutator
is rough or out-of-round, it should be turned down,
do not undercut or turn to less than 1 .650" O.D .
Inspect the points where the armature conductors
join the commutator bars to make sure they have a
good connection . A burned commutator bar is usu-
ally evidence of a poor connection .
6. If test equipment is available:
a. Check the armature for short circuits by
placing on growler and holding hack saw blade over
armature core while armature is rotated. If saw blade
vibrates, armature is shorted. Recheck after cleaning
between the commutator bars . If saw blade still vi-
brates, replace the armature .
b. Using a test lamp, place one lead on the
shunt coil terminal and connect the other lead to a
ground brush. (figure 73).
NOTE : This test should be made from both
ground brushes to insure continuity through
both brushes and leads. If the lamp fails to light,
the field coil is open and will require repair or
replacement.
c . Using a test lamp, place one lead on the
series coil terminal and the other lead on the in-
sulated brush. (figure 74) If the lamp fails to light,
the series coil is open and will require repair or re-
placement.
NOTE : This test should be made from each in-
sulated brush to check brush and lead con-
tinuity.
d. Using a test lamp, place one lead on the
grounded brush holder and the other lead on either
ENGINE ELECTRICAL 6Y- 65
Figure 73-Checking Shunt Field Coil
insulated brush. (figure 75) If the lamp lights, a
grounded series coil is indicated and must be re-
paired or replaced .
e. Check the current draw of the solenoid
winding as follows : (figure 76).
If solenoid is not removed from starting motor,
the connector strap must be removed from the termi-
nal on the solenoid before making these tests. Com
plete tests in a minimum of time to prevent
overheating of the solenoid .
To check hold-in winding, connect an ammeter
and a variable resistance in series with a 12-volt bat-
tery and the "switch" terminal on the solenoid . Con
nect a voltmeter to the "switch" terminal and to
ground . Adjust the voltage to 10 volts and note the
ammeter reading. It should be 14 .5 to 16 .5 amperes.
Figure 74-Checking Series Field Coil