3. With the voltmeter negative lead connected to
Armature Open Circuit Test
the starter terminal of the starter relay and the
An open circuit armature may sometimes be
positive lead connected to the positive terminal
detected by examining the commutator for evidence of
of the battery (Figure 2, connection (3))...0.3 volt.
burning. A spot burned on the commutator is caused by
4. With the voltmeter negative lead connected to
an arc formed every time the commutator segment,
the negative terminal of the battery and the
connected to the open circuit winding, passes under a
positive lead connected to the engine ground
(Figure 2,. connection (4)) , 0. I volt.
Starter Load Test
Connect the test equipment as shown in Figure 3 Be
sure that no current is flowing through the ammeter and
heavy-duty carbon pile rheostat portion of the circuit
(rheostat at maximum counterclockwise position) Crank
the engine with the ignition OFF. and determine the
exact reading on the voltmeter. This test is accomplished
by disconnecting and grounding the high tension lead
from the ignition coil, and by connecting a jumper from
the battery terminal of the starter relay to the ignition
switch terminal of the relay.
Stop cranking the engine. Then reduce the
the same reading as that obtained while the starter
cranked the engine. The ammeter will indicate the
Armature and Field Grounded Circuit Test
starter current draw under load.
This test will determine If the winding insulation has
Starter No-Load Test
been damaged, permitting a conductor to touch the
The starter no-load test will uncover open or shorted
frame or armature core.
windings, rubbing armature. and bent armature shaft.
To determine if the armature windings are grounded
The starter can be tested, at no-load, on the test bench
make the connections as shown in Figure 5. If the
only Make the test connections as shown in Figure 4 The
voltmeter indicates any voltage, the windings are
starter will run at no-load. Be sure that no current is
flowing through the ammeter (rheostat at maximum
Grounded field windings can be detected by making
counterclockwise position). Determine the exact reading
the connections as shown in Figure 6 If the voltmeter
on the voltmeter.
indicates any voltage, the field windings are grounded.
FIG. 4 Starter No-Load Test on Test Bench
Disconnect the starter from the battery. Then, reduce
FIG 6 Field Grounded Circuit Test
the resistance 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