Glow plug circuit dash element function?

[PCweber]

Can someone explain what the function of the little heater eliment in the dash is to the glow plug system? I realize if it is a cold dark night you can see it get red hot but 95% of the time we use these machines during daylight hours and get no valid feedback from this device. Does it also perform some type of vairable resistance function in the circuit to protect the plugs or something?

 

[Milton Burro]

If I'm not mistaken, it indicates when the glow plugs are receiving power from the electrical system. In cold weather, I turn my key to the left just enough to light this indicator for a few seconds to preheat the plugs before I try and start the engine. Depending on how cold it is determines how long I preheat the plugs. If it's below freezing, I hold for ten seconds or thereabouts.

 

[KennyV]

Does it also perform some type of vairable resistance function in the circuit to protect the plugs or something?

You hit it exactly, variable resistance ...
That element is in series with the glow plugs... As it heats the resistance increases and allows you to hold the glow plugs on for a long time without chancing burning out the glow plugs...
KennyV