GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: OnStar Schematics

Connector End View Reference: Entertainment/Communication Connector End Views

DEFINITION: The OnStar® Call Center operator can clearly be heard but the operator is unable to hear the caller.

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

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 Conditions and Poor Connections

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the cellular microphone connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the cellular microphone signal circuit to a good ground.

Does the voltage measure greater than the specified value?

9 V

Go to Step 4

Go to Step 5

4

Measure the voltage from the cellular microphone signal circuit to the drain wire circuit.

Does the voltage measure greater than the specified value?

9 V

Go to Step 7

Go to Step 6

5

Test the cellular microphone signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

6

Test the drain wire circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

7

Test the drain wire for a short to ground.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

8

  1. Leave the microphone disconnected.
  2. Disconnect the vehicle communication interface module (VCIM) connector C2.
  3. Test the cellular microphone signal circuit and drain wire circuit for a short together.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

9

Inspect for poor connections at the harness connector of the cellular microphone. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

10

Inspect for poor connections at the harness connector of the VCIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

11

Replace the cellular microphone. Refer to Mobile Telephone Microphone Replacement .

Did you complete the replacement?

--

Go to Step 13

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12

Replace the VCIM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

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13

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2