A brilliant tool for the auto electrician and mechanic. Carry out the following tests on systems from 6Volt up to 24Volt quickly and efficiently:Polarity test.Power up components prior to fitting including: Cooling fan motors. Fuel pumps, Window/Sunroof motors. Relays and Lamps. Wiper motors.Tests continuity in: Switches. Diodes and Fuses. Relays. Wiring harnesses.Detect short circuits. Locate bad earths quickly.Fitted with a sensitive short circuit protection device. Safe to use around vehicles electronic management systems. Power switch self test means no need to: Double check your circuit, tester on the vehicles battery. Reconnect hook-up clips to test polarity. Search for earth points. Burn out fuses locating faults. Run voltage drop tests.Fitted with 4.5mtr of cable allowing access to the rear of the vehicle and supplied with instruction guide.