A voltage tester is a necessary tool for the installation of car alarms, car audio, additional lighting, reversing sensors, and more. The tester helps with any electrical repairs in the car. It allows you to check whether there is electricity to sockets, plugs, sockets, bulbs, sensors, fuses. The tester works properly in installations from 6V to 24V. voltage tester is a helpful tool that can save you time and money by allowing you to quickly and easily check for voltage before beginning any electrical repairs.