B1686 – OBD-II DTC

OBD-II DTC B1686 – Lamp Dome Input Circuit Open

DTC B1686 meaning

DTC B1686 refers to a diagnostic trouble code indicating an issue with the Lamp Dome Input Circuit. Specifically, it signifies that there is an open circuit in the input signal from the dome lamp switch to the vehicle’s body control module (BCM). This can prevent the dome lights from functioning correctly, affecting the vehicle’s interior lighting system.

DTC B1686 symptoms

Common symptoms associated with DTC B1686 may include:

• Dome lights not illuminating when doors are opened
• Dome lights remaining on continuously
• Interior lighting malfunctioning
• Possible related warning lights on the dashboard

DTC B1686 causes

Several factors can lead to the occurrence of DTC B1686, including:

• Faulty dome lamp switch
• Damaged wiring or connectors in the dome lamp circuit
• Defective body control module (BCM)
• Corrosion or poor connections in the circuit

DTC B1686 seriousness

The seriousness of DTC B1686 can vary. While it may not affect the vehicle’s drivability, it can lead to safety concerns due to inadequate interior lighting. Additionally, it may indicate underlying electrical issues that could affect other systems in the vehicle.

How to diagnose DTC B1686

To diagnose DTC B1686, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the code.
2. Inspect the dome lamp switch for proper operation.
3. Check the wiring and connectors for damage or corrosion.
4. Test the continuity of the circuit from the dome lamp switch to the BCM.
5. Examine the BCM for any faults or error codes.

How to fix DTC B1686 step-by-step instructions

To fix DTC B1686, follow these steps:

1. Repair or replace any damaged wiring or connectors found during diagnosis.
2. If the dome lamp switch is faulty, replace it with a new one.
3. Ensure all connections are clean and secure to prevent corrosion.
4. If the BCM is determined to be defective, replace it with a compatible unit.
5. Clear the DTC using an OBD-II scanner and test the system to ensure proper operation.

How to erase DTC B1686

To erase DTC B1686, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the vehicle to verify that the code does not reappear.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.