Mirror Driver Horizontal Switch Circuit Failure
The side mirror's horizontal adjustment motor or its control switch isn't communicating properly with the vehicle's control module. It's like a broken remote control—the command is sent, but the mirror doesn't respond.
The ECU monitors the voltage signal from the mirror switch circuit when the horizontal adjustment button is pressed. It expects a valid signal within a specific voltage range; if the signal is absent, shorted, or out of range for too long, a fault is logged.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Switch Signal Voltage | 0.5V to 4.5V (varies by position) | Open circuit (5V+) or short to ground (0V sustained) |
| Motor Current Draw | 1-5 amps during movement | No current or excessive current (>8A) |
Code B1737 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B1737 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.