What Does B2321 Mean?
This code indicates that the Body Control Module (BCM) has detected an open circuit in the feedback potentiometer for the driver's side mirror horizontal adjustment motor. The potentiometer provides position feedback to the BCM so it knows where the mirror is positioned during adjustment. An open circuit means the BCM is receiving no signal or an out-of-range signal from the horizontal position sensor, preventing proper mirror adjustment and position memory functionality.
Common Causes
40%
Broken or corroded wiring between the BCM and the mirror assembly, often caused by the flexible harness in the door hinge area flexing repeatedly
35%
Failed horizontal position feedback potentiometer inside the mirror assembly due to wear or internal open circuit
15%
Corroded or loose electrical connector at the mirror assembly or door junction
10%
Failed BCM with internal open circuit on the mirror control circuit
Diagnostic Steps
1
Step 1: Perform a visual inspection of the mirror wiring harness, particularly in the door hinge area where wires flex during door operation. Check for broken, chafed, or damaged wires and inspect all connectors for corrosion, bent pins, or loose connections.
2
Step 2: Using a digital multimeter, backprobe the mirror connector and check for continuity between the horizontal potentiometer signal wire and ground with the mirror disconnected. Refer to wiring diagrams for proper pin identification. An open circuit (infinite resistance) confirms the potentiometer or its wiring has failed.
3
Step 3: With the mirror connected, measure the resistance of the horizontal feedback potentiometer while manually moving the mirror glass horizontally. The resistance should vary smoothly between approximately 1-10k ohms (typical range). No change or infinite resistance indicates a failed potentiometer.
4
Step 4: Check continuity of the potentiometer signal wire from the mirror connector back to the BCM connector. Wiggle the harness in the door hinge area while testing to identify intermittent opens. Repair any breaks in the harness.
5
Step 5: If all wiring tests good, verify proper voltage supply (typically 5V reference) from the BCM to the mirror potentiometer. If no reference voltage is present, suspect BCM failure. If voltage is present but potentiometer shows open circuit, replace the mirror assembly.
6
Step 6: After repairs, clear codes, operate the mirror through full range of horizontal motion, and verify proper operation and that the code does not return.
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an open circuit in the feedback potentiometer for the driver's side mirror horizontal adjustment motor. The potentiometer provides position feedback to the BCM so it knows where the mirror is positioned during adjustment. An open ci...
The most common cause of B2321 (Mirror Driver Horizontal Feedback Potentiometer Circuit Open) is: Broken or corroded wiring between the BCM and the mirror assembly, often caused by the flexible harness in the door hinge area flexing repeatedly
Typical repair costs for B2321 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects power mirror adjustment convenience features. The mirror can still be manually positioned if needed, though memory functions and automatic adjustment will not work until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2321 to identify the root cause.
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Quick Info
Category
Body
System
Power Mirror Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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