B1736 — Mirror Driver Vertical Switch Circuit Short To Ground

OBD-II trouble code B1736 indicates a fault within the circuit that controls the vertical adjustment switch for the driver’s side mirror. This code typically suggests a short circuit to ground somewhere in the wiring or switch assembly. While the specifics of the label can vary depending on the vehicle manufacturer, this diagnostic trouble code points to a problem in the mirror adjustment system that may affect the driver’s ability to precisely position their mirror.

Fast Facts:

System affected: Exterior Mirrors – Driver Side Vertical Adjustment
Severity: Moderate – requires inspection but may not immediately impair driving
Main symptoms: Inoperative mirror adjustment, warning lights or messages
Driveability: Limited – primarily affects comfort and safety features related to mirror positioning

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Manufacturer variations for trouble code B1736

Different automakers may assign unique labels or codes for similar issues related to mirror switch circuits. It’s important to check the specific vehicle’s service manual or OBD-II system definitions, as these variations help technicians accurately identify and diagnose the problem.

Ford: B1736 – Mirror Adjustment Circuit Short to Ground
Volkswagen: 009873 – Mirror Switch Circuit Malfunction
BMW: 4D66 – Mirror Adjustment Control Circuit Short
GM (Chevrolet, GMC, Cadillac): B1736 – Mirror Driver Vertical Switch Fault
Mercedes-Benz: A000000 – Mirror Control Circuit Issue

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What does trouble code B1736 mean?

In simple terms, the ECU (Engine Control Unit or cabling control module) is monitoring the electrical circuit that operates the vertical adjustment switch of the driver’s side mirror. When this system detects an abnormality—such as a short circuit to ground—it triggers this code. A short to ground occurs when the electrical current flows unintendedly directly to the vehicle’s chassis or another grounded component, bypassing the switch normally responsible for the mirror’s vertical movements.

This fault may have been caused by damaged wiring, a faulty switch, or a connector problem. This code often appears when attempting to adjust the mirror after electrical issues, or if there’s been recent work on the door or mirror assembly. If left unresolved, it could lead to the mirror being inoperative or other electrical issues within the mirror system.

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Severity and risks of trouble code B1736

The presence of B1736 is generally considered a moderate issue. The main risk is that the driver’s mirror vertical adjustment may be permanently inoperative or behave erratically. This can impair the driver’s situational awareness, especially in situations requiring precise rearward visibility, such as parking or lane changes.

In terms of vehicle operation, this diagnostic trouble code does not typically affect drivability or safety-critical functionality outside of mirror adjustment. However, if the mirror adjustment system is entirely unreliable, it could increase the risk of blind-spots or misjudging distances, which are safety concerns.

**Can the vehicle be driven?** Yes, with limitations. The vehicle remains drivable, but addressing the fault will improve comfort and safety.

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Symptoms of trouble code B1736

When this code is stored, some common symptoms include:

Inoperative driver side mirror adjustment: The vertical control never responds.
Warning indicators: Dashboard lights or messages related to mirror malfunction may appear.
Mirror position irregularities: The mirror may move unexpectedly or be stuck in a certain position.
Electrical issues: Other mirror-related features (like heating or auto-dimming) could be affected depending on wiring integrity.

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Most likely causes of trouble code B1736

Understanding what causes B1736 can help target repairs efficiently. Typically, this fault arises from issues in wiring or switches associated with the mirror’s vertical adjustment function.

Damaged or frayed wiring: Wires that supply power and ground to the mirror switch may be worn, broken, or pinched, leading to a short circuit.
Faulty mirror switch: The switch itself may be internally damaged or malfunctioning, creating a short circuit to ground.
Connector issues: Corrosion, loose pins, or poor contacts within the connector harness can cause intermittent shorts or open circuits.
Internal wiring harness short: Damage within the vehicle’s door wiring loom connecting the mirror to the vehicle body.
Previous repairs or impact damage: Impact or improper repairs can disturb wiring or switch contacts, leading to shorts.

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How to diagnose trouble code B1736

Proper diagnosis involves a systematic approach to verify the fault and locate its source. Always follow safety procedures, disconnect batteries if necessary, and use appropriate diagnostic tools.

Visual inspection: Examine the wiring harness, connectors, and switch for visible damage, corrosion, or loose pins.
Check wiring continuity: Use a multimeter to verify continuity between the switch, wiring, and ground points, looking for shorts or open circuits.
Inspect the switch: Remove and test the mirror adjustment switch for proper operation and internal damage.
Live data testing: Connect a scan tool able to read live sensor data and observe the mirror adjustment signals when toggling the switch.
Scan for other related codes: Check if other mirror or electrical circuit-related codes are present, which might point to a broader wiring or control module issue.

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Possible repairs for trouble code B1736

Once the diagnosis confirms the cause, repairs can be planned accordingly. Many repairs are straightforward but might require professional intervention depending on vehicle complexity.

Replacing damaged wiring or connectors: This is a basic repair, often performed by technicians or skilled DIYers with electrical experience.
Replacing the mirror adjustment switch: A straightforward swap if the switch itself is faulty, typically a professional repair for critical wiring or integrated modules.
Correcting connector issues: Cleaning or re-seating connectors, or replacing damaged terminals, is a common, non-invasive repair.
Repairing or replacing wiring harness segments: For extensive damage within the door or mirror wiring loom, a professional repair or harness replacement might be necessary.
ECU or control module update/reprogramming: Rarely needed, but required if the fault is linked to a software glitch—best performed by dealers or qualified technicians.

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Vehicles commonly associated with trouble code B1736 in Europe

The B1736 code is generally seen in European vehicles from various brands that feature electrically adjustable side mirrors. These vehicles tend to belong to the following groups:

Volkswagen Group (Volkswagen, Audi, Skoda, SEAT): Many models with electric mirrors may report this code, especially those with advanced mirror control systems.

Ford: Various models equipped with electric mirrors and mirror adjustment modules.

BMW: Especially models from the E and F series with electric side mirrors.

Mercedes-Benz: Vehicles with electronically controlled mirrors may register this fault.

Note: Exact model offerings vary, and this list is not exhaustive. Always refer to the specific vehicle’s wiring diagrams and service bulletins for more precise information.

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Frequent mistakes with trouble code B1736

Diagnosing and repairing this fault can be complicated by common errors. Recognizing these can save time and prevent unnecessary repairs.

Ignoring the root cause: Jumping straight to switch replacement without inspecting wiring or connectors may not resolve the issue.
Assuming the switch is fine based on visual inspection alone: Internal switch faults may not be visible; testing with a multimeter or scan tool is essential.
Replacing wiring without confirming the fault: This can lead to unnecessary expense and time-consuming work.
Overlooking related modules or other electrical issues: Sometimes, the fault is within the control module or other interconnected circuits.
Not following proper safety procedures: Working with electrical systems without disconnecting batteries or using insulated tools can be hazardous.

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FAQ — trouble code B1736

Can this code disappear on its own?

Typically, no. B1736 indicates a persistent electrical fault that won’t resolve spontaneously. However, temporary glitches may sometimes clear if the wiring issue is intermittent and resolves itself, but this is uncommon. Persistent faults need proper repair.

Can I keep driving?

Yes, generally, you can continue driving, as this fault mainly affects mirror adjustability. However, reliability of the mirror operation is compromised, which could impact safety. It’s advisable to investigate and repair the fault promptly.

Why does the code return after clearing?

This often indicates an unresolved underlying cause, such as a wiring short, faulty switch, or connector problem. Until these issues are fixed, the fault will likely regenerate when the vehicle’s system rechecks the circuit.