WOMS
P code powertrain Medium severity

P1628 Module Ignition Supply Input Malfunction

The OBD2 code P1628 indicates a malfunction in the ignition supply input to the engine control module (ECM), which may affect the module's ability to receive proper power for operation

Definition

The OBD2 code P1628 indicates a malfunction in the ignition supply input to the engine control module (ECM), which may affect the module's ability to receive proper power for operation

Common causes

  • Faulty ignition switch
  • Damaged wiring or connectors
  • Failed powertrain control module (PCM)
  • Poor ground connection
  • Malfunctioning relay
  • Short circuit in the ignition supply circuit
  • Battery voltage issues

Common misdiagnoses

  • Faulty ignition switch
  • Bad battery connections
  • Defective powertrain control module (PCM)
  • Wiring issues or shorts in the ignition circuit
  • Faulty relays or fuses
  • Incorrectly installed aftermarket accessories
  • Malfunctioning key or immobilizer system
  • Issues with the engine control module (ECM)

Troubleshooting steps

  1. 1. Check the Battery Voltage

  2. 2. Ensure the vehicle's battery is fully charged and in good condition. Low voltage can cause various electronic issues

  3. 3. Inspect Fuses

  4. 4. Check the fuses related to the ECM and ignition system. A blown fuse can interrupt the power supply to the module

  5. 5. Examine Wiring and Connectors

  6. 6. Inspect the wiring harness and connectors for any signs of damage, corrosion, or loose connections. Pay special attention to the wiring leading to the ECM and ignition system

  7. 7. Test the Ignition Switch

  8. 8. Verify that the ignition switch is functioning properly. A faulty ignition switch can prevent the ECM from receiving the necessary power

  9. 9. Check for Ground Issues

  10. 10. Ensure that the ECM has a good ground connection. A poor ground can lead to erratic behavior and trigger fault codes

  11. 11. Scan for Additional Codes

  12. 12. Use an OBD-II scanner to check for any other related trouble codes. This can provide additional context for the issue

  13. 13. Inspect the ECM

  14. 14. If all other components check out, the ECM itself may be faulty. Consider testing or replacing the ECM if necessary

  15. 15. Look for Short Circuits

  16. 16. Check for any short circuits in the wiring that could be causing the malfunction. This may require a multimeter to test continuity and resistance

  17. 17. Review Technical Service Bulletins (TSBs)

  18. 18. Check for any TSBs related to your vehicle make and model that might address known issues with the ignition supply or ECM

  19. 19. Perform a Reset

  20. 20. After addressing any issues, clear the trouble codes and see if the P1628 code returns. Sometimes, a reset can resolve temporary glitches. 1

  21. 21. Consult a Professional

  22. 22. If the issue persists after performing these steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the underlying issue causing the P1628 code