Faulty Glow Plugs
Glow Plugs harness is open or shorted
Glow Plugs circuit poor electrical connection
Faulty Glow Plug Controller
Engine Light ON (or Service Engine Soon Warning Light)
Lack/Loss of Power
The engine may be harder to start
The glow plug controller has the ability to perform internal diagnostics for the voltage and output state of the glow plugs. If the glow plug controller senses an open in the main battery supply to the glow plug controller or a condition with any of the glow plug driver circuits, the glow plug controller will send an error message to the Engine Control Module (ECM). The Diagnostic Trouble Code (DTC) will set when the glow plug controller detects an open to the main battery supply for the glow plugs, or an open in all 8 glow plug circuits for less than 1 second.