How Do I test Coil on Plug Ignition ?

This can be technical as explained in the video. Simply put, the coil is mounted directly to the plug boot eliminating the need for a plug wire. If you just need to find which one has failed, you can unplug each one separately while the engine is running and listen for engine change. Also you can use an Automotive Scan Tool and read the codes or look at the data to find the failed coil assembly.