Motorola Moto X Pure Edition Troubleshooting Manuals page 58

Secondary Microphone
If the Secondary MIC is not functioning ...
- Check MIC bias at C4510 or C4514 or C4513. This should be 1.7~1.8V when the microphone is
enabled.
- Check the 2 nd microphone sealing cushion at rear housing. If the cushion has been shifted, the MIC
hole could be blocked while it has been assembled.
- Check the microphone output at C4511 or C4512. The AC amplitude should increase (Output DC
bias should be around 0.7V), when audio is present.
MOTOROLA CONFIDENTIAL
Moto X Pure Edition/Moto X Style
Baseband TROUBLESHOOTING GUIDES