GM Service Manual Online
For 1990-2009 cars only

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 Conditions and Poor Connections in Wiring Systems

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 in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

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 Conditions and Poor Connections and Connector Repairs in Wiring Systems.

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 Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

12

Replace the Microphone assembly. Refer to Mobile Telephone 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 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