The glow plug monitor type preheating device is composed of glow plug, glow plug monitor, glow plug relay and other components. When the glow plug is hot, the glow plug monitor on the dashboard will display it.
The glow plug monitor is installed on the dashboard to monitor the heating process of the glow plug. The glow plug has a resistor connected to the same power source. And when the glow plug turns red, this resistor also turns red at the same time (usually, the glow plug monitor should glow red for about 15-20s after the circuit is turned on). Several glow plug monitors are connected in parallel. Therefore, if a glow plug is short-circuited, the glow plug monitor will glow red earlier than normal. On the other hand, if a certain glow plug is open, it will take a long time for the glow plug monitor to turn red. Heating the glow plug for a specified time will damage the glow plug monitor.
The glow plug relay can reduce a large amount of current through the starter switch, and the voltage drop caused by the glow plug monitor will not affect the glow plug. The glow plug relay actually includes two relays: when the starter switch is in the G (preheat) position, one of the relay current passes through the glow plug monitor to the glow plug; when the switch is in the START position, the other A relay delivers the current directly to the glow plug without passing through the glow plug monitor. This reduces the voltage caused by the resistance of the glow plug monitor during the start-up process .
