STARTER AND SOLENOID TROUBLESHOOTING

TM 10-3930-638-24&P

3-10. STARTER AND SOLENOID TROUBLESHOOTING (cont)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

Probable

Inspection

Armature

Current

Speed

Draw

Data

cause

Zero

Check internal connections and field coils for open

Open field circuit.

condition.

Inspect commutator for badly burned bars after

Open armature coils.

disassembly.

Poor brush contact.

Check for broken brush springs, worn brushes,

and high insulation between commutator bars.

Zero

Grounded terminals or fields.

High

Disconnect field coil ground connections and check

for grounded condition.

Frozen bearings.

Rotate armature by prying pinion with a

screwdriver.

High internal resistance.

Low

Check for poor connections, defective leads, and

dirty commutator.

High

Excessive friction.

Low

Check for tight, dirty, or worn bearings, bent

armature shaft or loose pole shoes allowing

armature to drag.

Shorted armature.

Check armature in a growler after disassembly.

Grounded field coils or

Disconnect field coil ground connections and check

armature.

for grounded condition.

High

Shorted field coils.

Replace field coils and repeat bench test.

2. STARTER FAILS TO CRANK

Step 1. Disconnect and tape field coil lead at solenoid M terminal.

Connect solenoid terminals to test set-up as shown.

Close switch, adjust carbon pile for 9 Vdc indication on

voltmeter, and note ammeter reading.

a. If ammeter indicates 6.5 to 7.0 amperes, proceed

to step 2.

b. If ammeter does not indicate 6.5 to 7.0 amperes,

replace solenoid switch (para 3-13).

Step 2. Reconnect solenoid terminals to pull-in winding test

set-up as shown on following page.

CAUTION

To prevent overheating solenoid, do not close switch for more

than 15 seconds at a time.

Close the switch and adjust carbon pile for 20 Vdc indication on voltmeter.

Note ammeter reading and open switch.

3-91