Check your RPO codes. If it has K60 then you have a 100 amp alternator.
The device is used to detect the presence or absence of voltage prior to working on a circuit. The red test probe is placed in contact with the "hot" wire and the black probe is placed in contact with the ground wire. If there is current, the neon bulb will glow and a solenoid will "buzz". The K-60 identifies both AC and DC current.
If you are using this device to check to see if the circuit is energized or not, it will work fine. The voltage range on this tester can be used from 120 volts up to 600 volts AC and DC. At the 600 volt range the unit can be left on the line for only 10 seconds and then be not used again for five minutes to let the internal solenoid plunger coil cool down.