WOMS
P code powertrain Medium severity

P0384 Glow Plug Control Module Control Circuit High

The OBD2 code P0384 indicates that the glow plug control module is detecting a high voltage in the control circuit, which may suggest a malfunction in the glow plug system or wiring

Definition

The OBD2 code P0384 indicates that the glow plug control module is detecting a high voltage in the control circuit, which may suggest a malfunction in the glow plug system or wiring

Common causes

  • Faulty glow plug control module
  • Open or shorted wiring in the control circuit
  • Poor electrical connections
  • Faulty glow plugs
  • Blown fuse
  • Corroded connectors
  • Malfunctioning engine control module (ECM)
  • Grounding issues

Common misdiagnoses

  • Faulty glow plugs
  • Bad glow plug relay
  • Wiring issues or shorts in the circuit
  • Faulty engine control module (ECM)
  • Incorrectly diagnosed fuel system issues
  • Battery or charging system problems
  • Faulty ignition switch
  • Misdiagnosed sensor issues (e.g., coolant temperature sensor)

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context for the issue

  2. 2. Inspect the Glow Plug Control Module

    Locate the glow plug control module and visually inspect it for any signs of damage, corrosion, or loose connections

  3. 3. Ensure that the module is securely mounted and that all connectors are clean and free of debris

  4. 4. Test the Glow Plugs

    Check the resistance of each glow plug using a multimeter. A typical resistance value is usually between 0.5 to 5 ohms, but refer to the vehicle's specifications

  5. 5. Replace any glow plugs that are out of specification

  6. 6. Check Wiring and Connectors

    Inspect the wiring harness and connectors leading to the glow plug control module and glow plugs for any signs of wear, fraying, or damage

  7. 7. Look for any loose or corroded connections that could cause a high resistance in the circuit

  8. 8. Test the Glow Plug Control Module

    If the wiring and glow plugs are in good condition, test the glow plug control module itself. This may require specific diagnostic tools or procedures as outlined in the vehicle's service manual

  9. 9. Check for proper voltage and ground at the module's connectors

  10. 10. Check Power and Ground Circuits

    Use a multimeter to check for proper voltage at the glow plug control module. Ensure that the module is receiving the correct voltage from the battery

  11. 11. Verify that the ground connections are solid and free of corrosion

  12. 12. Inspect the Engine Control Module (ECM)

    If all other components check out, the issue may lie with the engine control module. Check for any software updates or known issues related to the ECM

  13. 13. Clear Codes and Test Drive

    After performing repairs or replacements, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  14. 14. Seek Professional Help

    If you are unable to resolve the issue after following these steps, it may be best to consult a professional mechanic or technician who has experience with diesel engines and glow plug systems. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0384 code