Starter Testing

Starting System Voltage Drop Tests
NOTE: The battery must be in good condition and fully charged prior to performing this test.

There are three areas of the starter motor circuits that a voltage drop test can be performed on. These include:

1) The starter feed circuit
2) The starter ground circuit
3) The starter solenoid.

Starter Feed Circuit
1) Disable the fuel system by removing the fuel pump fuse or the fuel pump relay.
2) Verify that the vehicle will not start.
3) Connect the positive lead of a voltmeter to the positive terminal of the battery.
4) Connect the negative lead of a voltmeter to the starter B+ terminal.
5) Turn the ignition key to the START position and note the voltage displayed on the voltmeter.
A) Ideally, there should be no more than 0.1 volt drop for each connection displayed on the voltmeter. No voltage should be consumed by the vehicle wiring
B) If the battery cable connects directly to the starter motor there should be no more than a 0.2 volt drop measured
C) If the vehicle uses a starter solenoid between the battery and the starter motor terminal there should be no more than 0.4 volt displayed on the voltmeter.

Starter Ground Circuit
1) Disable the fuel system by removing the fuel pump fuse or the fuel pump relay.
2) Verify that the vehicle will not start.
3) Connect the positive lead of the voltmeter to the case of the starter motor.
4) Connect the negative lead of the voltmeter to the negative terminal of the battery.
5) Turn the ignition key to the START position and note the voltage displayed on the voltmeter.
A)Ideally, there should be no more than 0.1 volt drop for each connection displayed on the voltmeter. No voltage should be consumed by the vehicle wiring.
B) If the battery cable connects directly to the starter motor there should be no more than a 0.2 volt drop measured.

Starter Solenoid
1) Disable the fuel system by removing the fuel pump fuse or the fuel pump relay.
2) Verify that the vehicle will not start.
3) Connect the positive lead of the voltmeter to the case starter B+ terminal.
4) Connect the negative lead of the voltmeter to the lug (the starter M terminal) that connects the starter solenoid to the starter motor.
5) Turn the ignition key to the START position and note the voltage displayed on the voltmeter.
A) Ideally, there should be no more than 0.2 volt drop across the starter solenoid displayed on the voltmeter.
B) In general, there should be no more than a 1.0 volt drop throughout the entire starter motor feed and ground circuit. Any voltage drops measured in either the feed or ground circuits after connections have been cleaned will require replacement of the affected battery cable. Typically, any voltage drops measured in the solenoid are repaired by replacing the starter motor.

NOTE: Many automotive parts stores have starter bench testers available for use by customers. A starter bench test is the most definitive way to determine the condition of your starter.