What does it mean?
B2385 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Horn Switch Output Circuit High .
Symptoms
- Navigation voice prompts are drowned out because the audio never ducks
- Radio or media mutes permanently as soon as navigation guidance is active
- Voice guidance is missing entirely while the map still displays normally
- Audio volume jumps up and down unpredictably during route guidance
- The problem started after a head unit, amplifier or navigation module was swapped
Likely causes
- Open or short in the navigation mute request wire between the navigation unit and the head unit or amplifier
- Loose or corroded terminals in the connector shared by the navigation and audio units
- Failed mute output driver inside the navigation module
- Harness damage under the centre console or behind the glovebox where the modules are mounted
- Missing or wrongly wired mute link after a navigation unit retrofit or replacement
- Software or variant mismatch between the navigation unit and the audio system
- Faulty mute input inside the audio unit
How to fix it
- Check the navigation voice guidance settings and its separate volume level before assuming a wiring fault
- Trigger a voice prompt and measure the mute line at the audio unit connector to see whether it switches at all
- Compare the same signal at the navigation module output to isolate which side is failing
- Test the wire for continuity, shorts to ground and shorts to power along its full length
- Inspect every connector that was disturbed during previous console or audio work
- Verify the modules are the correct variants and are coded to each other where the system requires it
- Replace the module whose output or input is proven dead once the harness has been cleared