GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC C Pickup - 2WD 🢒 Body and Accessories 🢒 Cellular Communication 🢒 OnStar Operator Unable to Hear Caller

Test Description

The following numbers refer to the steps in the table.

  1. This step that the OnStar® call will go through. It is possible that the call may take up to 3 minutes to complete.

    2.

  2. This checks the operation of the microphone. 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.

  3. This step inspects that the microphone circuit from the Microphone to the VIU.

    4.

  4. This step inspects Microphone circuit between the VIU and the VCU.

Step

Action

Value(s)

Yes

No

DEFINITION: This is for a inoperative or poor performance of the Hands-free microphone.

1

Did you preform the OnStar® Diagnostic System Check?

--

Go to Step 2

Go to OnStar System Check

2

  1. Turn On the ignition with the engine OFF.
  2. Activate the OnStar® Call button.

Does the "Connecting to OnStar®" message play?

--

Go to Step 3

Go to OnStar System Check

3

When you hear the OnStar® Call Center operator, speak clearly into the OnStar® Microphone.

Can the operator hear you clearly?

--

Go to Step 10

Go to Step 4

4

  1. Disconnect the OnStar® Microphone.
  2. Turn the ignition to ON with the engine OFF.
  3. Measure voltage at the OnStar® Microphone from the Cellular Telephone Microphone Signal circuit to the Drain Wire circuit.

Is voltage near the specified value?

9 volts

Go to Step 5

Go to Step 7

5

Test the XCVR MIC IN circuit for an open or a short. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

Replace the OnStar® Microphone. Refer to Hands-Free Microphone Replacement .

Did you complete the replacement?

--

Go to Step 10

--

7

Test the Cellular Telephone Microphone Signal circuit for a short or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 8

8

Test the Drain Wire circuit for a short or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

9

Replace the VIU. Refer to Vehicle Interface Unit and Vehicle Communication Unit Modules Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2