WOMS
B code body Medium severity

B1277 Servo Motor Potentiometer Foot Circuit Open

The OBD2 code B1277 indicates that there is an open circuit in the servo motor potentiometer for the foot control, which may affect the operation of the throttle or brake system

Definition

The OBD2 code B1277 indicates that there is an open circuit in the servo motor potentiometer for the foot control, which may affect the operation of the throttle or brake system

Common causes

  • Faulty servo motor potentiometer
  • Open or damaged wiring in the foot circuit
  • Poor electrical connections or corroded terminals
  • Malfunctioning accelerator pedal position sensor
  • Issues with the engine control module (ECM) or powertrain control module (PCM)

Common misdiagnoses

  • Throttle position sensor failure
  • Accelerator pedal position sensor issue
  • Wiring harness problems
  • Faulty brake pedal position sensor
  • Electronic control unit (ECU) malfunction
  • Servo motor failure
  • Grounding issues
  • Connector corrosion or damage
  • Software calibration errors
  • Other potentiometer circuit faults

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are multiple issues

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring and connectors associated with the accelerator pedal position sensor and the servo motor

  4. 4. Look for signs of damage, corrosion, loose connections, or frayed wires

  5. 5. Ensure that all connectors are securely plugged in

  6. 6. Test the Potentiometer

  7. 7. Use a multimeter to test the resistance of the potentiometer. It should show a variable resistance as the pedal is pressed and released

  8. 8. Check for an open circuit by measuring resistance at different pedal positions. If the resistance does not change or shows an open circuit, the potentiometer may be faulty

  9. 9. Check Power and Ground

  10. 10. Verify that the potentiometer is receiving the correct voltage and ground. Use a multimeter to check for power at the connector while the ignition is on

  11. 11. Ensure that the ground connection is solid and free of corrosion

  12. 12. Inspect the Accelerator Pedal Assembly

  13. 13. Check the entire accelerator pedal assembly for any mechanical issues, such as binding or obstruction that could affect the movement of the pedal

  14. 14. Ensure that the pedal returns to its resting position properly

  15. 15. Test the Servo Motor

  16. 16. If applicable, test the servo motor for proper operation. This may involve checking for power and ground at the motor and ensuring it responds correctly when the pedal is pressed

  17. 17. Clear Codes and Test Drive

  18. 18. After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner

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

  20. 20. Refer to the vehicle's service manual for specific testing procedures and specifications related to the accelerator pedal position sensor and servo motor

  21. 21. Seek Professional Help

  22. 22. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1277 code