Starter Motor: Testing and Inspection

Basic checks
1 Use a voltmeter to check that at least 12 V is present directly across the battery terminals.
If it is not, test the battery.
2 Use a voltmeter to check that at least 12 V is present across terminal 30 on the starter motor and the negative battery terminal.
3 Use a voltmeter to check that operating voltage is present on the +50 terminal.
If it is not, check the wiring between the battery and the starter motor.




Checking the starter motor when it is in operation
Voltage at the battery
1 Connect a voltmeter across the battery terminals.
2 Start the engine and read off the instrument.
A reading of at least 10 V should be obtained.
3 If the voltmeter shows less than 10 V the battery must be recharged.




Voltage drop in a circuit
1 Connect a voltmeter across:
- the positive battery terminal and terminal 30 on the starter motor;
- the positive battery terminal and terminal 50 on the starter motor (voltage in the starting position only);
- the negative battery terminal and the starter motor casing.
Start the engine and read off the voltmeter. The reading obtained should not exceed 0.2 - 0.3 V.
2 If a circuit shows a higher reading it should be checked to determine the reason for the excessive voltage drop.