Bluetooth Microphone Poor Performance

Some 2019 Silverado 1500, Sierra 1500; and 2020 Silverado 2500/3500 HD and Sierra 2500/3500 HD models may have a poor or degraded Bluetooth call performance heard by the person on the end of the call (not in the vehicle). The person being called may tell the caller in the vehicle that the line has a crackling noise. DTC B127C-04 (Microphone 2 Input Signal Circuit) may be set in the radio.

The sound may be due to poor terminal tension, or deformed or bent terminals in the passenger-side wiring harness at the B24RF right-front mobile telephone microphone connector. (Fig. 21)


Fig. 21


Inspect the B24RF microphone connector for any damaged terminals. Also check the mated bodies for any unseated terminals.

If any damaged terminals are found, replace the connector with leads. If no damage is found, follow the appropriate Service Information for additional diagnostic procedures.

Refer to Bulletin #19-NA-152 for additional details and parts information.


– Thanks to Jeremy Richardson


Updated August 30, 2019


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