P0683 - GLOW PLUG CONTROL MODULE TO PCM COMMUNICATION CIRCUIT CODE

Unlike a gasoline engine that needs a spark to catch fire the fuel, diesel motors are based on extremely high compression. Diesel compresses the air inside the cylinders until the air reaches high enough temperatures to easily ignite the fuel. But if a diesel engine block is cold, very little heat is created through compression to ignite the fuel.

If the Powertrain Control Module (PCM) detects that the engine is cold through oil signals and transmission temperature sensors, it commands the glow plugs to ignite.

Basically, the diagnostic code P0683 OBDII means that communication between the Glow Plug Control Module (GPCM) and the Powertrain Control Module (PCM) circuit has been lost. The fault prevents the PCM from commanding the Glow Plug Control Module. This command is important as it is an on/off signal.

• Illuminated service light.
• It increases fuel consumption.
• Unstable engine running at idle.
• Acceleration deficiency.
• Excessive smoke from the exhaust.

The DTC code P0683 OBD2 is established by the following:

• Open or short circuit in the cables of the Glow Plug Control Module (GPCM).
• Faulty ignition.
• There may be poor connections.
• Error in the glow plug control module.
• The glow plug solenoid may be in bad shape.
• The battery power to the solenoid may be insufficient.

When faced with the fault code P0683 OBD II, you must do the following for its proper correction:

• Check the cables from the Powertrain Control Module (PCM) to the Glow Plug Control Module (GPCM). Also, check the solenoid wires in the valve cover. If any of these electrical components are worn or corroded, repair or replace them.
• Unplug the black and green electrical connector from the GPCM and check it for defective pins and corrosion.
• Using an ohmmeter, check if the terminals are well-grounded. If they're short, repair them.
• Check the positive of the battery as well as the connection to the GPCM on the glow plug solenoid. Check that all cables are tightened correctly.
• Check the glow plug bus bar. Make sure the connections on each cable are in good condition.
• Use the ohmmeter to check the glow plug terminal. To do this, put a connector on one wire and the other on the ground. If the resistance is not between 0.5 and 2.0 ohms, it indicates that the glow plug is malfunctioning.