unplug the harness that goes in the valve cover there are 4 of the same color wires on each side i think that they are white but cant remember.take a 12v test light and put the clamp on your positive batt cable then take the test light and put it on each glowplug wire if it lights up your glowplug has at least some life in it but i bet you wont have to many of that happening from what i have read above.