WOMS
P code powertrain Medium severity

P068B ECM/PCM Power Relay De-Energized Performance

The OBD2 code P068B indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a performance issue with the power relay that supplies power to the ECM/PCM, specifically that it has...

Definition

The OBD2 code P068B indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a performance issue with the power relay that supplies power to the ECM/PCM, specifically that it has been de-energized when it should be energized

Common causes

  • Faulty ECM/PCM power relay
  • Wiring issues or short circuits
  • Faulty ECM/PCM
  • Poor ground connections
  • Battery voltage issues
  • Corroded or damaged connectors
  • Faulty ignition switch
  • Software issues or updates needed

Common misdiagnoses

  • Faulty ECM/PCM
  • Bad power relay
  • Wiring issues or shorts
  • Battery or charging system problems
  • Faulty ignition switch
  • Poor ground connections
  • Corroded connectors
  • Software issues or updates needed
  • Fuel system problems
  • Sensor malfunctions

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 and help identify related issues

  2. 2. Inspect the Battery and Connections

    Ensure the battery is fully charged and in good condition

  3. 3. Check battery terminals and connections for corrosion or looseness

  4. 4. Inspect the ground connections to the ECM/PCM and ensure they are secure and free of corrosion

  5. 5. Examine the Power Relay

    Locate the ECM/PCM power relay in the fuse box or relay panel

  6. 6. Inspect the relay for any signs of damage or wear

  7. 7. Swap the relay with a similar one (if available) to see if the issue persists

  8. 8. Check Fuses

    Inspect the fuses related to the ECM/PCM and the power relay. Replace any blown fuses

  9. 9. Test the Relay Operation

    Use a multimeter to test the relay for proper operation. Check for continuity and ensure it is functioning as intended

  10. 10. Inspect Wiring and Connectors

    Check the wiring harness and connectors leading to the ECM/PCM and the power relay for any signs of damage, fraying, or corrosion

  11. 11. Ensure all connectors are securely attached

  12. 12. Check for Short Circuits

    Look for any short circuits in the wiring that could cause the relay to de-energize unexpectedly

  13. 13. Test the ECM/PCM

    If all other components check out, the ECM/PCM itself may be faulty. Testing or reprogramming the ECM/PCM may be necessary

  14. 14. Consult a professional technician for advanced diagnostics if needed

  15. 15. Clear Codes and Test Drive

    After performing repairs, clear the trouble codes using the OBD-II scanner

  16. 16. Take the vehicle for a test drive to see if the code reappears

  17. 17. Consult Repair Manual or Professional Help

    If the issue persists after following these steps, consult the vehicle’s repair manual for specific troubleshooting procedures or seek assistance from a qualified mechanic. By following these steps, you should be able to identify and resolve the issue related to the P068B code. Always ensure safety precautions are taken when working on a vehicle's electrical system