Diagnostic Aids

If glow plug relay is stuck in ON position, check for proper operation of glow plugs. When glow plugs are commanded ON by scan tool, an internal ECM timer protects glow plugs from damage by cycling them ON for 3 seconds and then OFF for 12 seconds. Most glow plug system failures are covered by DTC P0380. If no DTCs are stored, vehicle is hard to start, White smoke is present during cranking or after vehicle is started, the most likely cause of failure is glow plugs.