I am not sure that I understand the use of the Glow Plugs. I know that they heat the fuel pre-chamber for starting. But do they stay on after that at just a lower power? I am changing my GP's tomorrow and I just went out to put a test light on the main power wire, and both sides of the fuse and all was well with the key turned one click. I had my wife turn it until the GP light came on and started testing the five connectors on the relay and still had power after the dash light had gone out. Is this right??

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1985 300D burning WVO using 26 FPHE, half gallon heated fuel filter,glow plug heater,home made injection line heaters. Home made cold air induction. ALDA full out.
2003 F350 7.3(the last of the great motors)
1987 Paint Horse-non running too, just walks!