B1720 — Seat Driver Forward Switch Circuit Short To Ground

The diagnostic trouble code B1720 indicates a problem with the driver’s seat forward switch circuit, specifically a short to ground. This means that the electrical circuit associated with the switch that controls the seat’s forward movement is experiencing an unintended direct connection to ground, causing the vehicle’s ECU (Engine Control Unit) to register an error. It’s important to note that labeling may vary between manufacturers, but the core diagnosis remains similar.

Manufacturer variations for trouble code B1720

Depending on the vehicle manufacturer, the trouble code related to the driver’s seat forward switch circuit may be labelled differently. Manufacturers often assign their own specific codes or descriptions, although the underlying issue remains similar across brands.

• Volkswagen / Audi / Skoda / Seat: 08477
• Ford: B1720
• Mercedes-Benz: 2214
• BMW: 9850
• Honda: B1720
• Others: May have similar code numbering or descriptions referencing seat switch circuits or short to ground

What does trouble code B1720 mean?

B1720 is a code recognized by the vehicle’s On-Board Diagnostic (OBD-II) system, which monitors the electrical circuits related to the seat’s position adjustment mechanisms. The ECU has detected a short circuit to ground in the circuit that controls the driver’s seat forward switch.

In simple terms, this means that the electrical pathway designed to send signals when the driver presses the seat forward button is experiencing an unexpected connection to ground, possibly due to damaged wiring or a faulty switch.

This code typically appears when there is a problem with the wiring harness, a defective switch, or a component in the control module responsible for moving the seat forward.

The code often triggers during or after seat adjustment attempts, especially if there was an abnormal resistance, jam, or wiring damage near the seat mechanism.

Severity and risks of trouble code B1720

B1720 generally indicates an electrical fault that can affect the functionality of the driver’s seat adjustment system. If left unresolved, the issue may prevent the seat from moving forward or trigger warning messages, impacting comfort and driving ergonomics.

From a safety perspective, this code does not directly affect the vehicle’s ability to operate but could interfere with driver comfort and proper seating position. In some cases, it might be part of a larger system controlling electronic seat adjustments, which could be critical for emergency or safety features.

**Is the vehicle driveable?** The answer depends on the system’s design. Typically, Limited — the vehicle can be driven, but seat adjustments may be disabled or limited. It is advisable to address the code promptly to restore full functionality and avoid further complications.

Symptoms of trouble code B1720

The presence of B1720 can manifest through various indicators. While some drivers may notice no obvious issues, common symptoms include:

• Warning lights: Seat system or general warning lights on the dashboard.
• Inoperative seat adjustment: The driver’s seat may not move forward or backward.
• Unusual seat behaviour: Sporadic seat movement or failure to respond to control inputs.
• Electrical smell or burning odor: In cases of wiring short circuits.
• Inconsistent system responses: Intermittent operation of seat adjustment switches.

Most likely causes of trouble code B1720

Understanding what causes B1720 can help in diagnosing and fixing the issue efficiently. Here are the most common causes, ordered from most to least probable:

1. Damaged or shorted wiring harness: The wiring connected to the driver’s seat forward switch has been frayed, pinched, or torn, leading to a short to ground.
2. Faulty seat forward switch: The switch itself may be internally damaged or worn out, causing improper electrical contact.
3. Corrosion or dirt in connectors: Poor connection due to corrosion, dirt, or debris in the electrical connectors at the switch or seat motor control module.
4. Control module malfunction: The electronic control unit managing the seat adjustment operation may have an internal fault.
5. Mechanical issues causing electrical strain: Jammed or stuck seat components can lead to abnormal electrical conditions.

How to diagnose trouble code B1720

Diagnosing B1720 involves systematic inspection of the electrical circuit and components associated with the driver’s seat forward switch. Here’s a general approach:

1. Visual inspection: Check the wiring harness and connectors for physical damage, corrosion, or loose connections.
2. Test the switch: Remove and test the driver’s seat forward switch with a multimeter to verify proper operation.
3. Check wiring continuity: Conduct continuity tests on the wiring from the switch to the control module to detect shorts or open circuits.
4. Use live data: With a diagnostic scanner, monitor seat switch signals during operation, observing for abnormal voltage or resistance patterns.
5. Inspect related components: Examine the seat motor, associated relays, and control modules for any signs of damage or malfunction.

Possible repairs for trouble code B1720

Fixing B1720 generally involves addressing the root cause identified during diagnosis. Common repairs include:

• Replacing damaged wiring or connectors: Basic repair requiring some electrical skill, suitable for a professional or experienced DIYer.
• Replacing the faulty seat forward switch: Usually straightforward, but requires removing the seat panel or cover.
• Cleaning or restoring connections: Corrosion removal and ensuring secure connections can prevent future issues.
• Reprogramming or replacing the control module: For cases where the ECU or seat control unit is faulty; typically requires specialised tools and professional expertise.
• Addressing mechanical issues: Fixing any jammed or obstructed seat movements to prevent electrical strain.

Vehicles commonly associated with trouble code B1720 in Europe

This code can appear in a variety of vehicle makes and models equipped with electric seat adjustment systems. Some of the more common brands and associated models include:

Volkswagen Group: Golf, Passat, Tiguan, Audi A3, Skoda Octavia, Seat Leon

Ford: Focus, Mondeo

Mercedes-Benz: C-Class, E-Class

BMW: 3 Series, 5 Series

Honda: Civic, Accord

*Note:* This is not an exhaustive list, and any vehicle with power-adjustable seats may develop this issue.

Frequent mistakes with trouble code B1720

When diagnosing and repairing B1720, certain pitfalls can lead to unresolved issues or further damage. Common mistakes include:

• Assuming the switch is always the problem: Failing to verify wiring and connectors first can waste time and resources.
• Replacing parts without proper testing: Swapping the switch or wiring harness without confirming the fault may not resolve the issue.
• Ignoring related components: Overlooking wiring damage or control module faults can result in recurrent codes.
• Not following safety procedures: Working with electrical components can pose risks; proper safety measures should always be taken.

FAQ — trouble code B1720

Can this code disappear on its own?

Typically, no. The B1720 code usually persists until the electrical short or fault is repaired. Temporary issues may clear, but underlying problems will likely cause the code to return.

Can I keep driving?

In most cases, yes. The vehicle can often be driven with this code present, but seat adjustment functions may be limited or inoperative. It is advisable to repair the issue to restore full system functionality and safety.

Why does the code return after clearing it?

This generally indicates an unresolved underlying cause such as wiring damage or a faulty switch. Until the root problem is addressed, the code will likely reappear.