Use multimeters and electronic tools in the diagnosis, service and installation of various parts of your vehicle. Some of these parts are computerized diagnostics tools that test a single system, such as your airbags. On the other hand, other tools have a more generalized purpose. For example, multimeters measure electrical properties of any circuit, usually current, voltage and resistance. That makes them useful for testing anything from your headlamps to your dynamo. Look for tools like soldering irons and electronic calipers here, too. If it turns out you do have an electrical problem, you can use these multimeters and electronic tools to rebuild the part and make sure it works before reinstalling it.