Can someone please explain the following to me:
With the glow plug on my Otto glowing, if I disconnect either the positive or negative glow plug driver lead from the 12 volt battery then re-connect it, the plug does not light up again. If, on the other hand, with the driver leads connected to the battery, I disconnect either the positive lead from the plug, or the earth (ground) lead from the body of the engine, then reconnect, the plug starts to glow again.
I am sure there is a logical explanation, but I just can't figure out what it is at the moment. All suggestions gratefully received!