Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The glow plugs provide a hot spot in the combustion chamber, and are used to aid in cold starting. The Glow Plug Control Module (GPCM) controls the glow plug temperature by regulating the current supplied to the glow plugs. The GPCM communicates with the PCM via the J1939 engine datalink, and the glow plug temperature and operation time is based on engine information supplied by the PCM. The GPCM monitors the status of each glow plug individually, and reports diagnostic failures to the PCM via the J1939 datalink. The glow plug system will be disabled when the fault is set. The PCM will turn OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and passes.