Mirror Driver Up Circuit Open
The mirror's up motor circuit has an open connection, like a broken wire preventing electricity from flowing. The ECU detects no signal returning from the mirror motor when it commands the mirror to move upward.
The ECU sends a command voltage to the mirror motor and monitors the return current draw through the up circuit. It expects to detect a specific voltage drop and current flow when the up command is activated. If no current is detected for the expected duration, an open circuit fault is logged.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Motor circuit current | 0.5-2.5 amps during up movement | Less than 0.1 amps or no current detected |
| Circuit voltage drop | 11-13 volts at motor | Battery voltage (no load) or 0 volts |
Code B1774 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, B1774 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.