Circuit/System Verification

NOTE:

It is necessary to have the vehicle in a quiet, open outside area where a cellular call can be successfully placed.

Ignition ON.
Verify that DTC B2455 is set.
- If DTC B2455 is not set
  Refer to OnStar Microphone Malfunction .
- If DTC B2455 is set
Verify that your voice can be heard clearly after placing a cellular call.
- If your voice can not be heard clearly
  Refer to Circuit/System Testing below.
- If your voice can be heard clearly
All OK.