B1277 – Servo Motor Potentiometer Foot Circuit Open

The ODBII 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.

The severity of ODBII code B1277 is moderate.

Common Causes For: B1276 Servo Motor Potentiometer Foot Circuit Failure

• 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 misdiagnosis for B1277 Servo Motor Potentiometer Foot Circuit Open

• 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

Common Troubleshooting Steps

The OBD-II code B1277 indicates a problem with the servo motor potentiometer in the foot circuit, typically related to the accelerator pedal position sensor or similar components. Here are some common troubleshooting steps to diagnose and resolve this issue:

• 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.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the accelerator pedal position sensor and the servo motor.
• Look for signs of damage, corrosion, loose connections, or frayed wires.
• Ensure that all connectors are securely plugged in.
• Test the Potentiometer:
• Use a multimeter to test the resistance of the potentiometer. It should show a variable resistance as the pedal is pressed and released.
• 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.
• Check Power and Ground:
• 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.
• Ensure that the ground connection is solid and free of corrosion.
• Inspect the Accelerator Pedal Assembly:
• Check the entire accelerator pedal assembly for any mechanical issues, such as binding or obstruction that could affect the movement of the pedal.
• Ensure that the pedal returns to its resting position properly.
• Test the Servo Motor:
• 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.
• Clear Codes and Test Drive:
• After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code reappears.
• Consult Service Manual:
• Refer to the vehicle’s service manual for specific testing procedures and specifications related to the accelerator pedal position sensor and servo motor.
• Seek Professional Help:
• 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.