[rotorwrench]

An inductive timing light will indicate when a high tension voltage is flowing in a plug wire if you want to check it but it may not give you the information you need. A high tension voltage has to have a ground path for it to flow. A bad spark plug may not provide a good ground path. A test with a good spark plug grounded to the head or with the high tension lead held with a gap to a ground source will confirm if the coil for that cylinder is doing its job. Take the plugs out and turn it by hand to test. This way it won't try to start on you. Once the timer reaches one of the terminals then the coil connected to that terminal will buzz and generate a high tension flow. It's not just one spark either. It will just keep sparking till the timer rolls off the terminal as long as the ignition is on battery.

High voltage release can bite you but only if you make yourself a ground path. If you insulate yourself far enough away from the high voltage terminal then it can't jump the gap to you.