Originally Posted by
Bush65
That is what is supposed to happen. The glow plug relay incorporates a timer to switch the current off.
I also think you don't need glow plugs in a 300Tdi - as long as engine compression is good (rings, valves, head gasket) and the starter cranks it properly, it should start.
Before you pull any glow plugs to replace them, disconnect the wires and use your multimeter to measure the resistance (ohms) between the electrical terminal of each glow plug and a good earth on head - those measurements will tell you which if any glow plugs are dead.