i dont know why it fried the plugs, the light never comes on while your driving it. it only comes on when you manualy push the button. as for as a bad batch of plugs i could see 1 or 2 but all 8. i have a solid state controller now so im going to swap it all over and get away from them 6volt plugs. has anyone ever used champion glow plugs? i know i wont touch another set of autolite plugs, bearly got them out the engine.