B1269 – Servo Motor Potentiometer Defrost Circuit Open

The ODBII code B1269 indicates a malfunction in the defrost circuit, specifically an open circuit in the servo motor potentiometer, which is responsible for controlling the defrost function in the vehicle’s climate control system.

The severity of ODBII code B1269 is moderate.

Common Causes For: B1268 Servo Motor Potentiometer Defrost Circuit Failure

• Open circuit in the potentiometer wiring
• Faulty servo motor potentiometer
• Poor electrical connections or corroded terminals
• Damaged or frayed wiring harness
• Failed HVAC control module
• Malfunctioning defrost control system

Common misdiagnosis for B1269 Servo Motor Potentiometer Defrost Circuit Open

• Faulty HVAC control module
• Defective servo motor
• Wiring issues or shorts
• Blower motor problems
• Incorrectly calibrated temperature sensors
• Faulty climate control switches
• Issues with the blend door actuator
• Low refrigerant levels
• Battery or charging system problems
• General electrical system faults

Common Troubleshooting Steps

The OBD-II code B1269 indicates a problem with the servo motor potentiometer circuit related to the defrost function in the vehicle’s climate control system. This code typically points to an open circuit or a malfunction in the potentiometer that controls the defrost actuator. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check for Additional Codes: Before proceeding, check for any other related trouble codes that may provide more context to the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring harness and connectors associated with the defrost servo motor and potentiometer. Look for signs of damage, corrosion, or loose connections.
• Ensure that all connectors are securely plugged in and that there are no broken wires.
• Test the Potentiometer:
• Use a multimeter to measure the resistance of the potentiometer. Compare the readings to the specifications provided in the vehicle’s service manual.
• If the resistance is outside the specified range, the potentiometer may be faulty and should be replaced.
• Check the Servo Motor:
• Test the defrost servo motor to ensure it is functioning correctly. You can do this by applying power directly to the motor and observing if it operates as expected.
• If the motor does not operate, it may need to be replaced.
• Inspect the Climate Control Module:
• The climate control module (or HVAC control module) may be malfunctioning. Check for any signs of damage or failure.
• If possible, perform a reset of the module or reprogram it according to the manufacturer’s instructions.
• Check for Ground Issues:
• Ensure that the ground connections for the servo motor and potentiometer are secure and free of corrosion. A poor ground can lead to erratic behavior and trigger fault codes.
• Look for Short Circuits:
• Inspect the wiring for any signs of short circuits that could cause the potentiometer circuit to register as open. This may involve checking for pinched wires or damaged insulation.
• Perform a System Reset:
• After addressing any issues found, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult the Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures and specifications related to the defrost circuit and potentiometer.
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has access to specialized diagnostic equipment. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1269 code.