This AutoAnalyzer performs all standard electrical tests for on-car and bench troubleshooting. Locate faulty wiring, test electrical components, engine sensors, ignition and fuel systems and starting/charging system voltage. Pinpoint problem area and determine which components need repair or replacement. This unit measures AC/DC voltage, DC current and resistance as well as tests diodes and batteries. Tests fuses, switches, solenoids and relays. The backlit LCD is easy to read day or night. The Hold button retains display data. The AutoAnalyzer also features automatic polarity sensing to avoid reversed test lead hook-up, automatic zero adjustment for volts, amps and battery tests for accurate measurements. A low battery indicator shows the user when it's time to change the 9v battery (not included).