GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Seville 🢒 Body and Accessories 🢒 Cellular Communication 🢒 OnStar Operator Unable to Hear Caller

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.

  1. This step verifies that the OnStar® 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.

    2.

  2. This step tests the microphone circuits from the microphone to the Cellular Telephone Module.

    3.

  3. This step tests the microphone circuit between the VIU and the vehicle communication unit) VCU.

Step

Action

Value(s)

Yes

No

1

Did you perform the OnStar® 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. Activate the OnStar® call button.
  3. When you hear the OnStar® Call Center operator, speak clearly into the Cellular microphone.

Can the OnStar® operator hear you clearly?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Place a call using the cellular telephone.
  3. When you hear the person you are calling, speak clearly into the Cellular microphone.

Can the person that you are calling hear you clearly?

--

Go to Step 4

Go to Cellular Telephone - Voice Inoperative During Hands-Free

4
  1. Disconnect the Cellular Telephone Module Harness.
  2. Turn the ignition to ON with the engine OFF.
  3. Measure voltage at the from the cellular telephone microphone signal circuit to the drain wire circuit.

Is voltage near the specified value?

9 volts

Go to Step 7

Go to Step 5

5

Test the cellular telephone microphone signal circuit between the VIU and the Cellular Telephone Module 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 6

6

Test the drain wire circuit between the VIU and the Cellular Telephone Module for 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 7

7

Test the XCVR MIC In circuit for a short B+, short to ground 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

Inspect for poor connections at the harness connector of the VIU. Refer to Testing for Intermittent Conditions and Poor Connections and Connector 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 OnStar Vehicle Interface Unit 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

--