The Coil On Plug (COP) tester is a battery operated hand-held quick tester designed to easily and quickly determine if a COP is producing a proper spark for the plug.
The quick tester works by receiving a signal from the secondary ignition coil. Once the signal is received, the tester determines if the COP is producing the correct amount of voltage and the duration of the arc. If the voltage is correct, the tester beeps and the red LED light flashes, and if the duration of the arc is correct, the green LED will also flash.