Originally Posted by Big Andy W
Yeah as he said, dissconnect the wires from the glow plugs and with a testlight, place the teslight wire on the positive terminal on the battery and put the probe on the electrical connection on the glow plug. If the test light lights then that plug is down.
Its just one continuios wire and when the relay clicks its showing correct voltage with multimeter!!
Yeah but all you are testing there is that the glow plug relay & supply is all ok & working, the plugs themselves could still be knackered and to determine this you need to do as i said above!