Mirror Passenger Left Circuit Failure
The passenger side mirror circuit is broken or disconnected, like a phone line that's been cut so no signal can get through. The car's computer detects the mirror isn't responding to commands or power signals.
The ECU sends voltage signals to the passenger mirror motor and monitors for proper current draw and response. It detects open circuits, shorts, or motor resistance outside normal operating parameters. If voltage is applied but no current flows, or resistance is infinite, the fault is logged.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Motor Circuit Current | 0.5-3.0 amps during operation | No current draw or >5 amps |
| Circuit Voltage | 12-14 volts supplied | 0 volts or open circuit detected |
Code B1639 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, B1639 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.