Testing the Battery
With the engine stopped, connect the tester's black clip to the negative (-) battery terminal, then touch the red lead to the positive (+) battery terminal.
1. If LEDs 1 through 3 light, the battery is good.
NOTE: Some late model or large vehicles might cause 4 LEDs to light. This is normal.
2. If fewer than 3 LEDs light, the battery needs maintenance.
3. If no LEDs light, the battery is totally dead and may be defective.

Testing the Alternator
Start the engine and run it at higher than normal idle.
1. If LEDs 1 through 5 light, the alternator is charging properly.
2. If fewer or more than 5 light, the vehicle's charging system might need maintenance.
NOTES:
1. For an accurate test, some vehicles might require a higher idle than others.
2. If you are testing the alternator in a cold environment, the "high output" light might come oneven though the alternator is operating properly.