6.5L diesel testing glow plug controller?

To test the glow plug controller on a 6.5L diesel engine, begin by ensuring the engine is off and the ignition is in the "off" position. Use a multimeter to check for voltage at the glow plug controller terminals while turning the ignition key to the "on" position; you should see voltage indicating the controller is functioning. Additionally, inspect the controller for any visible signs of damage or corrosion. If the voltage is absent or the controller appears faulty, it may need to be replaced.