Did you perform the OnStar® Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Cellular Communication

1. Turn on the ignition ON, with the engine OFF.
2. Turn ON the radio.
3. Set volume to a comfortable level.
4. Activate the OnStar® Center Call button.

Does "Connecting to OnStar" play through the audio system?

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

Go to Step 3

1. Turn on the ignition ON, with the engine OFF.
2. Turn ON the radio.
3. Set volume to a comfortable level.
4. Make a call Using the Cellular Phone.

Can you hear the person you are calling clearly?

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Go to Step 4

Go to Cellular Telephone - Audio Inoperative During Hands-Free

Test the Mono audio signal circuit between the VIU and the Cellular Telephone Module for short, an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the problem?

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Go to Step 8

Go to Step 5

Test the Mono audio common circuit between the VIU and the Cellular Telephone Module for short to ground, an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the problem?

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Go to Step 8

Go to Step 6

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?

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Go to Step 8

Go to Step 7

Replace the vehicle interface unit (VIU). Refer to OnStar Vehicle Interface Unit Replacement .

Did you complete the repair?

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Go to Step 8

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Operate the system in order to verify the repair.

Did you find and correct the condition?

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System OK

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