WOMS
P code powertrain High severity

P0681 ECM/PCM Power Relay Control Circuit Range/Performance Problem

The OBD2 code P0681 indicates a problem with the power relay control circuit for the Engine Control Module (ECM) or Powertrain Control Module (PCM), suggesting that the circuit is not operating within the expected range...

Definition

The OBD2 code P0681 indicates a problem with the power relay control circuit for the Engine Control Module (ECM) or Powertrain Control Module (PCM), suggesting that the circuit is not operating within the expected range or performance parameters

Common causes

  • Faulty ECM/PCM
  • Bad power relay
  • Wiring issues (shorts or opens)
  • Poor ground connections
  • Corroded connectors
  • Faulty ignition switch
  • Battery issues (low voltage)
  • Blown fuses

Common misdiagnoses

  • Faulty ECM/PCM
  • Bad power relay
  • Wiring issues or shorts
  • Battery problems
  • Grounding issues
  • Faulty ignition switch
  • Corroded connectors
  • Other electrical component failures

Troubleshooting steps

  1. 1. Check the Battery and Connections

    Inspect the Battery: Ensure the battery is fully charged and in good condition

  2. 2. Check Connections

    Look for any loose, corroded, or damaged battery terminals and connections. Clean and tighten as necessary

  3. 3. Inspect the ECM/PCM Power Relay

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

  4. 4. Visual Inspection

    Check for any signs of damage, corrosion, or burnt contacts

  5. 5. Test the Relay

    Swap the relay with a similar one (if available) to see if the problem persists. Alternatively, use a multimeter to test the relay for continuity and proper operation

  6. 6. Check the Relay Control Circuit

    Wiring Inspection: Inspect the wiring and connectors leading to the relay for any signs of damage, fraying, or corrosion

  7. 7. Voltage Test

    Use a multimeter to check for proper voltage at the relay terminals when the ignition is turned on. You should see battery voltage at the relay input

  8. 8. Inspect the ECM/PCM

    Check for Damage: Look for any signs of physical damage to the ECM/PCM

  9. 9. Connector Inspection

    Ensure that the connectors to the ECM/PCM are secure and free of corrosion or damage

  10. 10. Scan for Additional Codes

    Check for Other Codes: Use an OBD-II scanner to check for any other related trouble codes that may provide additional context for the issue

  11. 11. Test the Ground Circuit

    Ground Connections: Ensure that the ground connections for the ECM/PCM and relay are secure and free of corrosion

  12. 12. Ground Voltage Test

    Use a multimeter to check for proper ground voltage at the ECM/PCM

  13. 13. Check for Short Circuits

    Inspect Wiring: Look for any short circuits in the wiring harness that could be affecting the relay control circuit

  14. 14. Continuity Test

    Perform a continuity test on the wiring to ensure there are no breaks or shorts

  15. 15. Consult Wiring Diagrams

    Refer to Diagrams: Use the vehicle’s service manual to consult wiring diagrams for the ECM/PCM power relay circuit to ensure all components are functioning as intended

  16. 16. Replace Components as Necessary

    If any faulty components are identified (relay, wiring, connectors, or ECM/PCM), replace them as needed

  17. 17. Clear Codes and Test Drive

    After repairs, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.1

  18. 18. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0681 code