WOMS
P code powertrain Medium severity

P0689 ECM/PCM Power Relay Control Circuit Low

The OBD2 code P0689 indicates a problem with the power relay control circuit for the Engine Control Module (ECM) or Powertrain Control Module (PCM), specifically that the circuit is experiencing a low voltage condition

Definition

The OBD2 code P0689 indicates a problem with the power relay control circuit for the Engine Control Module (ECM) or Powertrain Control Module (PCM), specifically that the circuit is experiencing a low voltage condition

Common causes

  • Faulty ECM/PCM
  • Bad power relay
  • Open or shorted wiring in the control circuit
  • Poor ground connection
  • Blown fuse
  • Corroded connectors
  • Faulty ignition switch

Common misdiagnoses

  • Faulty ECM/PCM
  • Bad power relay
  • Wiring issues or shorts
  • Battery or charging system problems
  • Ignition switch failure
  • Ground connection issues
  • Faulty fuses
  • Sensor malfunctions

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 Battery Connections

    Look for corrosion, loose connections, or damaged cables at the battery terminals

  3. 3. Inspect Fuses

    Check Fuses: Locate the fuse associated with the ECM/PCM power relay and inspect it for continuity. Replace any blown fuses

  4. 4. Examine the Power Relay

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

  5. 5. Test the Relay

    Swap the relay with a similar one (if available) to see if the issue persists. You can also test the relay using a multimeter

  6. 6. Check Wiring and Connectors

    Inspect Wiring: Look for damaged, frayed, or corroded wires in the circuit leading to the ECM/PCM power relay

  7. 7. Check Connectors

    Ensure that all connectors are secure and free of corrosion or damage

  8. 8. Test the ECM/PCM

    Check for Faulty ECM/PCM: If all other components are functioning correctly, the ECM/PCM itself may be faulty. Use a scan tool to check for additional codes or issues

  9. 9. Reprogram or Replace

    If the ECM/PCM is determined to be faulty, it may need to be reprogrammed or replaced

  10. 10. Check Ground Connections

    Inspect Ground Wires: Ensure that all ground connections related to the ECM/PCM are secure and free of corrosion

  11. 11. Scan for Additional Codes

    Use a Diagnostic Scanner: Check for any other related trouble codes that may provide more context to the issue

  12. 12. Perform a Voltage Test

    Measure Voltage: Use a multimeter to measure the voltage at the ECM/PCM power relay. Ensure it meets the specifications outlined in the vehicle’s service manual

  13. 13. Consult the Service Manual

    Refer to Wiring Diagrams: Use the vehicle’s service manual to refer to wiring diagrams and specifications for the ECM/PCM power relay circuit

  14. 14. Professional Diagnosis

    If the issue persists after performing these steps, consider seeking help from a professional mechanic or technician who can perform more advanced diagnostics. By following these steps, you should be able to identify and resolve the issue related to the P0689 code. Always remember to take necessary safety precautions when working on a vehicle's electrical system