B1773 — Mirror Driver Up Circuit Failure

The diagnostic trouble code (DTC) B1773 indicates a problem within the electrical circuit responsible for the driver’s side mirror adjustment, specifically a failure in the circuit that controls the movement of the mirror when using the adjustment switch. This code suggests that the system detects an abnormality or open circuit preventing the mirror from moving in response to commands.

Note that exact labels and code descriptions may vary between vehicle manufacturers and OEMs. Always consult the specific vehicle’s repair manual for precise definitions.

Fast Facts

System affected: Mirror Adjustment Circuit
Severity: Moderate
Main symptoms: Inoperative mirror adjustment, warning messages
Driveability: No

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Manufacturer variations for trouble code B1773

The labeling of this diagnostic trouble code can differ depending on the vehicle manufacturer and the diagnostic system used. Some OEMs may present it with slightly different codes or descriptions, especially if proprietary or manufacturer-specific codes are used before universal OBD-II standardization.

Ford: B1773 – Mirror Driver Up Circuit Failure
Volkswagen/Audi: 1K4 959 593 D – Left Mirror Adjustment Circuit Malfunction
BMW: 9C83 – Mirror Adjustment Circuit Open/Short
Mercedes-Benz: B1773 – Driver Side Mirror Adjustment Circuit Fault

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What does trouble code B1773 mean?

This code means that the vehicle’s Electronic Control Unit (ECU), which is the vehicle’s central computer, has detected an issue in the electrical circuit responsible for moving the driver’s side mirror. Specifically, it monitors the circuit responsible for powering and controlling mirror adjustments. When there is an open circuit, short circuit, or loss of signal within the wiring or connector, the ECU records this fault.

The appearance of this code is typically triggered when the mirror fails to respond to the adjustment switch, coupled with a detection of abnormal voltage levels or no response within the control circuit. Drivers might notice their mirror becomes unadjustable, or an error message may appear on the vehicle’s dashboard.

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Severity and risks of trouble code B1773

This fault is generally classified as moderate in severity. It primarily affects the convenience and safety of the driver, as the mirror cannot be adjusted electronically. However, it does not directly impair core vehicle functions or safety systems like brakes or steering.

Potential risks are mainly limited to increased blind spots or difficulty in adjusting mirrors to optimal positions, especially in changing driving conditions or for different drivers. If left unaddressed, the fault could lead to more electrical issues over time, especially if it involves wiring damage.

Can the vehicle be driven? Yes. The vehicle remains drivable, but the mirror adjustment feature will be blocked until the fault is repaired.

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Symptoms of trouble code B1773

Common symptoms often linked to this code include the inability to electronically adjust the driver’s side mirror and the display of warning messages related to mirror control systems. A driver may notice the mirror remains fixed despite pressing the adjustment switch, and an alert light or message might appear on the dashboard sensors.

Inoperative driver’s side mirror adjustment via electric controls
Dashboard warning light or message related to mirror system
Mirror movement that is unresponsive to control inputs
Possible flickering or issues with the mirror’s indicator lights (if applicable)

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Most likely causes of trouble code B1773

This fault is usually caused by issues in the electrical circuit controlling the driver’s side mirror. Understanding the root causes can help focus repair efforts more efficiently.

Open or damaged wiring in the mirror adjustment circuit: Wiring may be cut, frayed, or pinched, preventing proper electrical flow.
Faulty mirror control switch: The switch that operates the adjustment might be defective or worn out.
Corroded or loose connector or wiring connection: Corrosion or poor contact can lead to intermittent or no electrical connection.
Malfunctioning mirror motor or actuator: The motor inside the mirror assembly could be faulty or have failed.
Control module or ECU malfunction: An internal fault within the vehicle’s body control module that manages mirror control circuits.

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How to diagnose trouble code B1773

To accurately identify the root cause of this issue, follow a systematic diagnostic approach:

Visual inspection: Check the wiring harness leading to the driver’s side mirror for obvious damage, corrosion, or disconnection.
Connector inspection: Ensure that all connectors are securely seated and free from corrosion or debris.
Test the switch: Use a multimeter or scan tool to verify that the mirror adjustment switch sends signals when operated.
Live data reading: Use an OBD-II scanner with live data capability to observe the status of the mirror control circuit when attempting adjustment.
Continuity test: Check the wiring continuity in the circuit between the switch, the mirror motor, and the control module.
Component testing: If necessary, test the mirror motor and actuator independently for proper operation.
Reset and clear codes: After repairs, clear codes and verify if the fault reappears during subsequent tests.

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Possible repairs for trouble code B1773

Based on the suspected causes, repairs can range from simple to complex. Here are typical actions:

Repair wiring or harnesses: Replace damaged wiring or connectors—this is a basic repair suited for DIY with proper tools.
Replace the mirror control switch: If faulty, the switch itself needs to be replaced, typically a relatively straightforward repair.
Clean or re-seat connectors: Ensuring all connectors are free from corrosion and properly connected can resolve the issue without further parts replacement.
Replace mirror motor or actuator: If the mirror motor has failed, replacing it involves removing the mirror assembly, which is often advisable to be done by a professional.
Control module troubleshooting: If the issue stems from the ECU or body control module, advanced diagnostics and possible software updates or replacements may be necessary—best handled by a professional technician.

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Vehicles commonly associated with trouble code B1773 in Europe

In European models, this code is found across various brands where electric mirror adjustments are standard. Typical vehicle groups include:

Volkswagen Group: Volkswagen, Audi, SEAT, Škoda – especially in models from the mid-2000s onwards using similar electrical architectures.

BMW: Many models in the 3 Series, 5 Series, and X series that feature electronic mirror controls.

Mercedes-Benz: Several models across different classes, particularly those equipped with power mirrors.

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Frequent mistakes with trouble code B1773

When diagnosing or repairing this fault, common errors can impede effective repair or cause reoccurrence. Recognising and avoiding these mistakes is essential for a successful fix.

Overlooking visual inspection: Failing to thoroughly check wiring and connectors can lead to missed root causes.
Assuming switch fault without testing: Replacing parts without confirming their condition wastes time and resources.
Ignoring grounding issues: Poor grounding points can cause electrical faults similar to open circuits.
Not clearing codes after repair: Failing to reset the ECU and verify the repair can result in false assumptions about the fix’s success.

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FAQ — trouble code B1773

Can this code disappear on its own? Usually not. Troubles in the mirror circuit tend to persist until repaired because they involve physical wiring or component failures.

Can I keep driving? Yes, but with limitations. The mirror adjustment system will be non-functional, which could affect visibility and safety. It is advisable to diagnose and fix the issue promptly.

Why does the code return after clearing it? If underlying causes such as wiring faults, connector corrosion, or faulty motors are unresolved, the fault code is likely to reappear once the system checks are performed again or the vehicle is powered off and back on.