B1684: Power Mirror Switch Circuit Open
The B1684 code indicates that the Body Control Module (BCM) or door module has detected an open circuit in the power, ground, or signal wire of the driver or passenger side mirror switch. This prevents the side mirrors from being adjusted electrically.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty mirror switch with an internal open circuit
- Damaged, corroded, or disconnected wiring or connectors between the switch and the door module/BCM
- Internal failure of the door module (DDM/PDM) or BCM
- Blown fuse in the mirror switch power circuit
3. Symptoms You Will Notice
- One or both power side mirrors do not respond to switch adjustments
- Mirror adjustment switch may feel loose or unresponsive
4. Step-by-Step Diagnosis
Check the mirror switch fuse and replace if blown
Inspect the mirror switch connector for corrosion, damage, or loose pins
Test the switch for continuity and proper voltage supply
Check wiring between the switch and door module/BCM for opens or shorts
If wiring and switch are good, test the door module or BCM for internal faults
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but you will not be able to adjust the side mirrors electrically. Manually adjust them before driving if possible.
How much does it cost to fix?▼
Repair costs vary widely: a switch replacement can be $50–$200, wiring repair $100–$300, and module replacement $200–$600, plus labor.