Turbo diesel plug light problem solved

Say all: If you ever start your diesel,and you know you have good glow plugs,and new relay.Then see no light,or it comes on from time to time.
It might be your water temp sender on the thermostat housing.My wire had come loose sometimes it touched.The plug will carefully open so you can attach new wire,and splice the old one.
Try this before the bloody knuckles and hands,getting glow plugs out.
Without the sender,the controller thinks the engine is hot.