For 1990-2009 cars

### Test Description

The number below refers to the step number on the diagnostic table.

1. If the remote radio audio output (-) circuit is shorted to voltage, then the vehicle communication interface module (VCIM) has been damaged and requires replacement.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: OnStar Schematics Connector End View Reference: Cellular Communication Connector End Views DEFINITION: This procedure is for diagnosing problems during OnStar® audio following a button press from the OnStar® button assembly.
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. Turn ON the radio.
3. Set volume to a comfortable level.
4. Press the OnStar® Center Call button.

Can the Connecting to OnStar message be heard playing through the audio system at all?

Go to Step 3

Go to Step 5

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
4 | Test the remote radio audio output (-) circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 12
5 | Does the radio mute once the OnStar® Call Center button is pressed? | Go to Step 6 | Go to Step 10
6 | Is any distortion heard? | Go to Step 8 | Go to Step 7
7 | Test the remote radio left audio signal 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 15 | Go to Step 8
8 | Test the remote radio left audio signal circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 9
9 | Test the remote radio audio output (-) circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 12
10 |

1. Turn OFF the ignition.
2. Disconnect the vehicle communication interface module (VCIM) connector C2.
3. Turn ON the ignition, with the engine OFF.
4. Turn ON the radio.
5. Set volume to a comfortable level.
6. Using a fused jumper, short the cellular mute signal circuit to a good ground.

Does the radio mute?

Go to Step 14

Go to Step 11

11 | Test the cellular mute signal circuit for an open. Did you find and correct the condition? | Go to Step 15 | Go to Step 13
12 | Inspect for poor connections at the harness connector of the VCIM. 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 15 | Go to Step 14
13 | Replace the radio. Refer to Radio Replacement in Entertainment. Did you complete the repair? | Go to Step 15 | --
14 | Important: Perform the OnStar® setup procedure. Replace the VCIM. Refer to Communication Interface Module Replacement . Did you complete the repair? | Go to Step 15 | --
15 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2