What does it mean?
B1775 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Microphone Input/Output Short to Power/Open .
Symptoms
- The person on the other end of a hands-free call cannot hear the driver, or hears only noise
- Voice control commands are not recognised at all
- Bluetooth pairs and audio plays through the speakers, but no voice is picked up
- Emergency call or telematics voice functions unavailable on equipped vehicles
- Loud hiss or crackle when a call is started
Likely causes
- Microphone connector left unplugged or half latched after headliner, mirror or overhead console work
- Broken conductor in the thin microphone lead where it bends at the A-pillar or headliner edge
- Water from a leaking sunroof drain or windscreen seal reaching the microphone and its connector
- Microphone element or its internal amplifier failed
- Aftermarket accessory wiring in the headliner shorted into the microphone pair
- Screened microphone cable chafed against a bracket so the signal wire touches a live conductor
- Audio or telematics module input stage failure
How to fix it
- Read the module codes and note whether the fault is present now
- Drop the overhead console or edge of the headliner and confirm the microphone connector is fully seated and dry
- Look for water tracks, damp foam or blocked sunroof drains above the microphone position
- Check continuity of both microphone wires from the module connector to the microphone, and check them for a short to a power feed
- Inspect the A-pillar and headliner routing for chafe against brackets or trim clips
- Fit a known good microphone if one is available to separate microphone from wiring
- Repair the harness or replace the microphone; replace the audio or telematics module only as a last step