Schematic Reference: OnStar Schematics

Did you perform the OnStar® Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Cellular Communication

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

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

Go to Step 10

Go to Step 3

Tune the radio to a known good station.

Can the audio be heard through all speaker channels?

Go to Step 4

Refer to Diagnostic Starting Point - Entertainment in Entertainment

Does the audio system mute?

Go to Step 6

Go to Step 5

Test the entertainment and comfort serial data 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 8

Test the remote radio left audio signal circuit for a short, an open or high resistance. 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

Test the remote radio audio output (-) circuit for a short to ground, an open or high resistance. 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

Inspect for poor connections at the harness connector of the vehicle interface unit (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

Important: Perform the OnStar® setup procedure.

Replace the VIU. Refer to OnStar Vehicle Interface Unit Replacement .

Did you complete the repair?

Go to Step 10

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Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

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