Operator Unable to Hear Caller - OnStar

Diagnostic Chart:

TEST DESCRIPTION
The following procedure tests for poor performance or an inoperative hands-free microphone.

The following numbers refer to the steps in the table.
2. This step verifies that the OnStar(R) call is successfully connected. The call may take up to 3 minutes to complete. The operator may say that this call is a "voice call with no data". This does not mean that the microphone is operating properly.
3. This step tests the microphone circuits from the microphone to the vehicle interface unit (VIU).
6. This step tests the microphone circuit between the VIU and the vehicle communication unit) VCU.