Mirror Switch Reference Voltage Fault
Diagnostic trouble code B2348 indicates a fault in the common positive reference voltage supply circuit for the rearview mirror switch. This circuit provides the necessary reference voltage for the power mirror control switches to operate correctly. The body control module (BCM) or mirror module detects an anomaly in the supply voltage, such as an out-of-range value, short circuit, or open circuit in the switch power wiring. This code is specific to Ford Motor Company and its associated brands, where the mirror system uses a shared reference voltage for multiple switch functions. The fault can cause the power mirrors to be unresponsive or operate erratically.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty mirror switch with internal short circuit
- Reference voltage circuit wiring shorted to ground or battery voltage
- Corroded or damaged mirror switch connector
- Open circuit in the reference voltage supply wiring
- Faulty body control module (BCM) generating the reference voltage
- Blown fuse or circuit breaker in the mirror circuit
3. Symptoms You Will Notice
- Power mirrors do not respond to switch inputs
- Mirrors move erratically or intermittently
4. Step-by-Step Diagnosis
Check for blown fuses in the mirror circuit and replace if necessary
Inspect the mirror switch connector for corrosion, damage, or loose pins
Test the reference voltage at the switch connector with a multimeter (should be ~5V or battery voltage per manufacturer specs)
Check for shorts to ground or battery in the reference voltage wire
If wiring and switch are good, test the BCM output or replace the BCM
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the severity is low. The vehicle remains drivable, but power mirrors may not function properly.
How much does it cost to fix?▼
Typical repair costs range from $100 to $400, depending on whether the issue is a simple fuse, a switch replacement, or a BCM replacement.