What Does B2349 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the negative reference voltage circuit for the power mirror switch assembly. The BCM supplies a reference ground or negative voltage to the mirror switch, and when this circuit is broken or disconnected, it cannot properly monitor mirror switch positions or commands. This prevents the BCM from receiving accurate mirror adjustment signals from the driver's door switch panel.
Common Causes
45%
Open circuit in wiring harness between BCM and mirror switch due to broken wire, damaged connector pins, or corrosion at connector terminals
30%
Failed or damaged mirror switch assembly with internal open circuit in reference voltage path
15%
Corroded or loose ground connection at BCM or ground distribution point in driver's door
10%
Failed Body Control Module with internal circuit fault on mirror switch reference voltage output
Diagnostic Steps
1
Step 1: Perform visual inspection of mirror switch connector and BCM connectors for signs of corrosion, bent pins, moisture intrusion, or physical damage. Check for proper connector seating and locking mechanisms.
2
Step 2: Using a digital multimeter, backprobe the mirror switch connector with ignition ON and measure voltage on the reference negative circuit terminal (consult wiring diagram for specific pin). Should read approximately 0-0.5V reference ground or specific negative voltage per manufacturer specification.
3
Step 3: If no voltage present, disconnect BCM connector and check for continuity between mirror switch reference negative terminal and corresponding BCM pin using multimeter in ohms mode. Reading should be less than 5 ohms. High resistance or infinite resistance indicates open circuit in wiring harness.
4
Step 4: Check BCM ground connections with multimeter, measuring resistance between BCM ground terminals and known good chassis ground. Should read less than 1 ohm. Clean and tighten ground connections if resistance is high.
5
Step 5: If wiring and grounds test good, disconnect mirror switch and measure resistance across switch terminals per wiring diagram specifications. Replace switch if resistance values are out of range or show open circuit.
6
Step 6: After repairs, clear codes, cycle ignition, operate mirror switches through all positions, and verify code does not return and mirrors function properly in all directions.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the negative reference voltage circuit for the power mirror switch assembly. The BCM supplies a reference ground or negative voltage to the mirror switch, and when this circuit is broken or disconnected, it cannot prop...
The most common cause of B2349 (Mirror Switch Reference Voltage Negative Common Open Circuit) is: Open circuit in wiring harness between BCM and mirror switch due to broken wire, damaged connector pins, or corrosion at connector terminals
Typical repair costs for B2349 range from $75 to $450, 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 functionality. Mirrors will remain in their current position but cannot be electrically adjusted, requiring manual adjustment before driving if mirror position is incorrect. Non-urgent repair unless mirrors are in unusable position.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2349 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body Control and Accessories
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
