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Microphone Inoperative - Caller Cannot Be Heard

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Microphone Inoperative - Caller Cannot Be Heard

Step Action Value(s) Yes No
Schematic Reference: OnStar Schematics 
DEFINITION: The OnStar® call center operator can clearly be heard but will advise the caller that they can not clearly hear them or can not hear them at all.
1 Did you perform the Cellular Communication Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Cellular Communication 
2
  1. Turn ON the ignition, with the engine OFF.
  2. Press the OnStar® call center button.
  3. Ask the OnStar® operator if your voice can clearly be heard.
Does the OnStar® operator hear your voice?		 - Go to TESTING FOR INTERMITTENT AND POOR CONNECTIONS Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the OnStar® Microphone.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the Cellular Telephone Microphone Signal circuit to a good ground.
Does the voltage measure near the specified value?		 9 V Go to Step 4  Go to Step 5 
4 Measure the voltage from the Cellular Telephone Microphone Signal circuit to the drain wire.
Does the voltage measure near the specified value?		 9 V Go to Step 7  Go to Step 6 
5 Test the Cellular Telephone Microphone Signal circuit for an open or a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 8 
6 Test the Drain Wire for an open. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 11 
7 Test the drain wire circuit for a short to ground. Refer to CIRCUIT TESTING and WIRING REPAIRS .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 9 
8
  1. Leave the microphone disconnected.
  2. Disconnect the VIU connector C1.
  3. Test the cellular telephone microphone signal circuit and drain wire circuit for a short together.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 9 
9 Test the microphone signal circuit between the VIU and VCU for an open or short to ground.
Did you find and correct the condition?		 - Go to Step 14  Go to Step 10 
10 Inspect for poor connections at the harness connector of the Microphone assembly. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
11 Inspect for poor connections at the harness connector of the VIU. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS and CONNECTOR REPAIRS .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 12 
12 Replace the Microphone assembly. Refer to OnStar Microphone Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13
IMPORTANT: Perform the OnStar® setup procedure.
Replace the VIU. Refer to OnStar Vehicle Interface Unit (VIU) Replacement .Did you complete the replacement?		 - Go to Step 14  -
14 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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