how do i locate a faulty glow plug. ?

If your multimeter can read current (amps) up to 20amp then if you disconnect the lead connected to the heater plug and connect the red lead of the meter to that and the black lead to the heater plug then you can see if the plug is drawing a current, when the ignition is switched on, no current = duff plug, but it might be quicker to just replace all the plugs

nigel
May 2010