B1737 — Mirror Driver Horizontal Switch Circuit Failure

The diagnostic trouble code (DTC) B1737 indicates a problem within the **circuit of the driver’s side mirror horizontal switch**. Essentially, the vehicle’s electronic control unit (ECU) detects an issue related to the switch that controls the mirror’s horizontal (left/right) movement. This code can be triggered by an open circuit, short circuit, or malfunctioning switch. Note that labels and coding may vary slightly between different vehicle manufacturers, but the underlying issue remains similar.

Manufacturer variations for trouble code B1737

The label or code for this issue can differ depending on the manufacturer, but **most OEMs** assign similar codes related to mirror switch circuits. Here are some known label variations:

• Ford: B1737 — « Mirror Switch Circuit Fault »
• Volkswagen: 5E2 953 503 — « Left Mirror Horizontal Adjustment Circuit »
• BMW: 61359534254 — Related to mirror switch circuit, may appear as a different code
• Honda: P0460 — (Note: Honda may use different codes, but for mirror circuits it can be similar)
• Other manufacturers: Codes may include « Mirror Control Circuit Fault, » « Mirror Switch Malfunction, » or numbered codes in similar ranges.

What does trouble code B1737 mean?

This code **means** that the vehicle’s ECU has detected a problem in the **electrical circuit associated with the driver’s side mirror’s horizontal adjustment switch**. Essentially, the ECU is monitoring the **integrity and operation** of the switch’s electrical circuit. When it detects an **open circuit (disconnection)**, a **short circuit (unexpected connection)**, or an **internal malfunction of the switch**, it flags the code.

The **ECU** constantly checks for **proper communication and function** of various switches for the exterior mirrors. The horizontal adjustment switch allows the driver to move the mirror left or right electronically. If the control signals are interrupted or inconsistent, the ECU perceives a fault and illuminates the **check engine light** or **setting a DTC** for diagnostics.

This fault can be triggered in various situations, such as a loose wire connector, a damaged switch, or a wiring harness problem. It often appears when attempting to adjust the mirror or may be detected during a routine diagnostic scan.

Severity and risks of trouble code B1737

The **severity** of this trouble code is generally considered **moderate**. It primarily impacts the **driver’s ability to adjust the side mirror electronically**, which can be inconvenient but typically does not directly threaten vehicle safety or drivability. However, being unable to properly adjust the mirror may impair **rearward visibility**, increasing the risk of **blind spots**.

In most cases, the vehicle can be driven without issue, but **functional mirror adjustment remains compromised**. If the issue involves a short circuit or wiring damage that could potentially cause electrical problems elsewhere, it’s advisable to address it promptly.

**Can the vehicle be driven?** — Yes, but with limited mirror adjustment functionality. It’s recommended to repair the issue to ensure full control over mirror positioning for safety reasons.

Symptoms of trouble code B1737

Often, the main symptom is related to the **failure of the mirror’s horizontal adjustment** via the switch. The issue may be noticed as follows:

• Inoperative horizontal mirror control: The mirror does not move left or right when the switch is engaged.
• Illumination of warning lights: Sometimes, a dashboard warning or mirror indicator may appear.
• Intermittent operation: The mirror adjustment may work inconsistently, especially if caused by loose wiring.
• No physical damage: There may be no external signs of damage to the switch or wiring.

Most likely causes of trouble code B1737

The causes of this issue generally fall into a few common categories. The list below ranks causes from most to least probable, assisting technicians and vehicle owners in focusing their diagnosis:

1. Faulty or worn driver’s side mirror horizontal switch: Switches can fail internally over time, especially with heavy use or moisture ingress.
2. Damaged wiring or connector: Corrosion, broken wires, or loose connectors can interrupt the circuit.
3. Blown or faulty fuse: A fuse protecting the mirror’s circuit may be blown, disrupting power or signals.
4. ECU or Body Control Module (BCM) malfunction: Less common but possible if multiple circuits have issues.
5. Short circuit or wiring shorting against other components: Electrical shorts caused by damaged insulation.

How to diagnose trouble code B1737

Identifying the precise cause requires careful, methodical inspection. Here are typical diagnostic steps:

1. Visual inspection: Check the wiring harness and connector at the mirror switch for signs of damage, corrosion, or loose connections.
2. Test the switch: Use a multimeter to verify continuity across the switch terminals when operated; replace if faulty.
3. Check fuses: Confirm that fuses associated with mirror control circuits are intact.
4. Verify wiring integrity: Perform continuity tests of wiring between the switch, fuse box, and ECU or BCM.
5. Monitor live data: Use a diagnostic scanner to observe the circuit states while operating the switch to see if signals are correctly sent.
6. Inspect the ECU/BCM: If all wiring and components are OK, further diagnostics on the vehicle’s central control modules may be necessary.

Possible repairs for trouble code B1737

Based on the diagnosis, several repairs may be needed. Some are simple and can be performed by the vehicle owner or technician, while others require professional intervention.

• Replace the faulty switch: If the switch is internally damaged, a basic repair. Suitable for DIY if accessible.
• Repair or replace wiring or connectors: Address corrosion or broken wires. Professional repair recommended if wiring harnesses are damaged.
• Replace blown fuses: If a fuse is blown, replacing it can resolve the issue. Ensure the cause of the fuse failure is also addressed.
• Repair or replace ECU/BCM: If the control module is faulty, repairs often require professional programming or replacement.
• Address wiring shorts or grounding issues: This may involve extensive diagnostics and repair by a qualified technician.

Vehicles commonly associated with trouble code B1737 in Europe

This code can appear in many vehicle brands, especially those with electrically adjustable mirrors. Typical models include recent versions from popular manufacturers:

• Volkswagen Group: Golf, Passat, Polo, Tiguan, and Audi models with electric mirror adjustments.
• Ford: Focus, Fiesta, Kuga, and Mondeo equipped with electrical mirror controls.
• BMW: 1 Series, 3 Series, and X models with electronic mirror adjustments.
• Honda: Civic and Accord (electric mirrors)
• Other brands: Many European and Japanese makes with electrical mirror systems might display similar codes.

Frequent mistakes with trouble code B1737

Diagnosing and repairing this issue can sometimes lead to common errors. Recognising these helps prevent misdiagnosis or unnecessary repairs:

• Ignoring loose or corroded wiring: Overlooking simple wiring issues that cause the fault.
• Replacing the switch without proper testing: Installing a new switch without confirming the original fault may result in ongoing issues.
• Assuming electronic control module failure too early: Modules are often healthy, with most issues rooted in wiring or switches.
• Failing to clear codes after repairs: Not resetting the ECU after fixing the issue can lead to confused diagnostics.

FAQ — trouble code B1737

Can this code disappear on its own?

No. If the wiring or switch fault persists, the code generally remains until the underlying issue is physically repaired. However, temporary glitches can sometimes clear after multiple ignition cycles.

Can I keep driving?

Yes, but with **limited mirror control functionality**. For safety and convenience, it’s best to repair the fault as soon as possible to regain full mirror adjustability.

Why does the code return after clearing it?

The fault is likely persistent—such as a damaged switch, wiring, or connector—that continually triggers the monitoring system. Clearing the code temporarily hides the problem but does not fix it, leading to reappearance.