Generator Testing

NOTE: Battery posts and cable clamps must be clean and tight for accurate meter indications.

When performing charging system tests, turn off all lamps and electrical components. Place transmission in neutral and apply the parking brake.

Generator On-Vehicle Tests - Base Voltage

NOTE: Prior to running this test, turn the headlamps on for 10-15 seconds to remove any surface charge from the battery. Then, wait until the voltage stabilizes before performing the test. The battery should be at the recommended state of charge.

1. With the ignition OFF and no electrical loads on, connect the ARBST voltmeter negative lead to the battery ground cable clamp.
2. Connect the positive lead of the ARBST to the battery to starter relay cable clamp.
3. Press the MULTIMETER button.
4. Read and record the battery voltage shown on the display. This is called base voltage and will be used in later tests.

Generator On-Vehicle Tests - No-Load
1. Connect the leads of ARBST across the battery terminals.
2. Press the MULTIMETER button.
3. Read the voltage (base voltage).
4. Start the engine and monitor the engine speed.
5. Run the engine at 1,500 rpm with no electrical load.
6. Read the voltage. The voltage should be in the range of 14.1 to 15.1 volts. If the voltage increase is less than 2.5 volts over the base voltage, perform the Load Test. If there is no voltage increase or the voltage increase is greater than 2.5 volts, perform the Generator On-Vehicle Tests - Load.

Generator On-Vehicle Tests - Load
1. With the engine running, turn on the air conditioner (if equipped), and turn the blower motor to high speed and the headlamps to high beam.
2. Increase the engine speed to approximately 2,000 rpm. The voltage should increase a minimum of 0.5 volt above the base voltage. If the voltage does not increase as specified, install a new generator.

If the voltage increases as specified, the charging system is operating normally.