With the game off. Clip/disconnect one of the wires going to the switch (make sure the clipped end is taped and doesn't contact any high voltage). See if the coil keeps firing. If that stops it more than likely it is the switch. You can verify it with an OHM meter. If that doesn't do it disconnect the switch wiring harness to the mpu. if it continues to fire your problem is likely on the board. Good luck.