No-Load Test

No-Load Test Connection:

CAUTION: Refer to Service Precautions.

CAUTION: Keep fingers and tools away from opening in Drive End (DE) housing while testing. The strong shifting action of the solenoid could cause personal injury or damage as the drive pinion moves into cranking position and spins.

1. Secure starting motor in vise or suitable test stand. With carbon pile load turned "off" and switch "open". make connections.
2. Turn switch on and adjust carbon pile load to the specified voltage (refer to "Specifications"). Read current draw on ammeter and pinion speed on RPM indicator. Turn off carbon pile and open switch. Compare readings to test specifications (refer to "Specifications").
^ Current draw and RPM readings within specifications indicate that the electrical portion of the starter motor is operating properly. To assure that starter will engage properly, check pinion clearance as described in "Pinion Clearance Check".
^ Low free speed and/or high current draw may indicate tight, dirty, or worn bushings or bearings; a shorted or grounded armature; or a grounded field.
^ High current draw with pinion moving into cranking position but no pinion rotation indicates that a direct ground in the field or "frozen" bushings or bearings.
^ No pinion movement and current reading of 60-85 amperes indicates plunger is unable to move into solenoid or drive is unable to move on armature shaft (often described as "click but no crank").
^ No pinion movement and very low or no current draw indicates an open in the solenoid winding.
^ Pinion moves into cranking position but does not turn, and very low current draw indicates an open in the field circuit or armature windings, or no current flow between the solenoid battery and motor field terminals while the motor is engaged. Add a jumper lead between the solenoid battery and motor field "M" terminals. If the motor now turns at the specified RPM, the starter solenoid is inoperative.
^ Low no-load speed and low current draw indicate high internal resistance due to: poor brush lead connections, a dirty commutator, an open in the armature windings, broken, weak brush springs, or worn brushes.
^ High no-load speed and high current draw indicates shorted field coils or shorted armature windings.

If the starter also vibrates or is noisy during the no-load test, the armature may be rubbing against the inside of the frame and field.