Glow Plugs

Glow plugs and the injection nozzle are installed in the pre combustion chamber of the cylinder head. The glow plug (heater plug) is turned on when you turn on the ignition switch. On some equipment a light on the dashboard signals that the glow plug is cycling which signals you to wait between 3 to 5 seconds before cranking the engine. The heat, created by electrical resistance in the glow plug, heats the fuel and air mixture, thus it is also known as a "Heater Plug". The heat generated by the glow plug and the heat generated by compression allow the fuel to ignite.
All glow plugs have the same purpose. The difference is quality! There are single coil and dual coil plugs. Single coil plugs will burn out if constant power is applied, while dual coil plugs will regulate their temperature and not burn out. dual coil regulates the plug's temperature to avoid catastrophic failures