Every vehicle is going to have to get serviced some point in time. But with this voltage test pen for automobiles, this tool can save you time. Professional auto mechanics, I'm sure are using this tool for general maintenance before working on your car. Suppose the circuit from your ignition switch isn't working properly. Therefore you can save time by starting testing the ignition switch circuit in your steering wheel.
All you have to do to use a circuit tester, is attach the crocodile earth clip to the negative terminal of a vehicles battery to the circuit tester probe to the positive one. I know you seen people get there car started by using other peoples car batteries with their automobiles,trucks, motorcycles,etc. You should not wait for your batteries die or electrical problems happen to get a diagnostics with your automobiles. You should keep an extra new battery in your vehicle in case you run into some sort of problem.
If the circuit tester light does not show, guess what? Your battery has expired in your vehicle. Circuit testers and voltage pens are useful in every step in general maintenance.