Caution: Keep fingers, tools, and any other objects away from the opening in the drive end housing while making electrical connections. The strong shifting action of the starter solenoid can cause severe personal injury or damage to components as the drive pinion moves into the cranking position.

Notice: Do not crank the starter motor for more than 30 seconds at a time. Cool for at least two minutes after cranking before continuing. Excessive cranking can cause serious damage to the starter motor as well as erroneous test results.

1. Remove the starter motor. Refer to Starter Motor Replacement .
2. Turn OFF the carbon pile.



3. Make connections as shown with the switch open.
4. Close the switch.
5. Adjust the carbon pile in order to obtain 10 Volts.
6. Compare the readings of the current, the RPM, and the voltage. Refer to Starter Motor Usage .
7. If the pinion does not shift into the cranking position or the pinion does not rotate, then turn OFF the switch immediately. Ensure that the test electrical connections were properly made. If so, then replace the starter motor.
8. If the starter motor energizes and the pinion rotates, then, while maintaining 10 Volts on the voltmeter, check the current draw on the ammeter and the pinion speed on the RPM indicator

•	Turn OFF the switch.

•	Compare the values to the starter specifications table. Refer to Starter Motor Usage .

-	If the current draw and the pinion speed (RPM) are within the specifications, then the starter motor is good.

-	If the current draw or the pinion speed (RPM) is not within the specifications, then replace the starter motor. Refer to Starter Motor Replacement .

The rated current draw and no load speed indicates normal starter motor operation. Use the following test results to determine abnormal starter motor conditions. If any of these conditions exist, replace the starter motor:

1. Low free speed and high current draw. This indicates too much friction, caused by one or more of the following conditions:

•	Worn, dirty, or tight bearings

•	A bent or shorted armature shaft

•	A grounded armature

•	Grounded fields

2. Failure to operate with a high current draw. This indicates one or more of the following conditions:

•	A direct ground in the terminal

•	A direct ground in the fields

•	Seized bearings

3. Failure to operate with no current draw. This indicates one or more of the following conditions:

•	An open field circuit

•	Open armature coils

•	Broken brush springs

•	Worn brushes

•	High insulation between commutator bars

•	Poor contact between the brushes and the commutator

4. Low no load speed and low current draw. This indicates one or more of the following conditions:

•	High internal resistance (due to poor connections)

•	Defective leads

•	A dirty commutator

•	An open field circuit

•	Open armature coils

•	Broken brush springs

•	Worn brushes

•	High insulation between commutator bars

•	Poor contact between the brushes and the commutator

5. High free speed and high current draw usually indicates shorted fields.