Starter Solenoid Test; Starter No-Load Bench Test; Armature Open Circuit Test; Armature And Field Grounded Circuit Test - Ford VSG-411 Service Manual

STARTER SOLENOID TEST
If the solenoid does not pull in, in the Starter Load Test,
measure the voltage between the starter-mounted solenoid switch
terminal and ground with the ignition switch closed. If the voltage
is 10 or more volts, a worn or damaged solenoid is indicated.
Remove the starter assembly for solenoid replacement.
BENCH TESTS
STARTER NO-LOAD TEST
The starter no-load test will uncover such faults as open or
shorted windings, rubbing armature, and bent armature shaft. The
starter can be tested, at no-load, on the test bench only.
Make the test connections as shown in Figure 3. The starter will
run at no-load. Be sure that no current is flowing through the
ammeter (rheostat at maximum counterclockwise position). De-
termine the exact reading on the voltmeter.
Disconnect the starter from the battery, and adjust the load of
the rheostat until the voltmeter indicates the same reading as that
obtained while the starter was running. The ammeter will indicate
the starter no-load current draw.
BATTERY
STARTER
TESTER
FIG. 3 Starter No-Load Test on Test Bench
ARMATURE OPEN CIRCUIT TEST
An open circuit armature may sometimes be detected by exam-
ining the commutator for evidence of burning. A spot burned on
the commutator is caused by an arc formed every time the com-
mutator segment, connected to the open circuit winding, passes
under a brush.
ARMATURE AND FIELD GROUNDED CIRCUIT TEST
The test will determine if the winding insulation has failed,
permitting a conductor to touch the frame or armature core.
To determine if the armature windings are grounded, make the
connection as shown in Figure 4. If the voltmeter indicates any
voltage, the windings are grounded.
Grounded field windings can be detected by first disconnecting
the grounded end of the winding where it terminates at the frame,
then making the connections as shown in Figure 5. If the voltmeter
indicates any voltage, the field windings are grounded.
TESTER
T
FIG. 4 Armature Grounded Circuit Test
BATTERY STARTER TESTER
f
FIG. 5 Field Grounded Circuit Test