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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Acadia - AWD 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 OnStar Audio Malfunction

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The radio is supplied with OnStar® a mono audio from vehicle communication interface module (VCIM). When the radio receives an audio signal from the VCIM the radio mutes the current audio signal and delivers an audio signal from the OnStar® system.

Reference Information

Schematic Reference

OnStar Schematics

Connector End View Reference

Entertainment/Communication Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification
  1. Tune radio to a known good station and verify that audio is heard clearly through all speaker channels.
    2. ⇒If audio is not heard clearly refer to Diagnostic Starting Point - Cellular, Entertainment, and Navigation .
  2. Ignition ON, radio ON, set volume to comfortable level and press OnStar® Center Call button.
  3. Verify Connecting to OnStar® message is heard clearly through the audio system.
    4. ⇒If OnStar® message is not heard, go to Circuit/System Testing (No OnStar® Audio).
    ⇒If OnStar® message is noisy or distorted, go to Circuit/System Testing (Noisy OnStar® Audio).

Circuit/System Testing (No OnStar® Audio)
  1. Ignition OFF, disconnect the X2 radio harness connector.
  2. Ignition ON, test for a momentary AC voltage (OnStar® audio signal) between the X2 connector terminal cavity 7 and 15 when the white dot button on the keypad is pressed.
    3. ⇒If a momentary AC voltage was present replace the radio.
  3. Ignition OFF, disconnect the X2 VCIM harness connector.
  4. Test for less than 1 ohm between the X2 VCIM connector terminal 1 and the radio X2 connector terminal 7.
    5. ⇒If more than the specified value repair open or high resistance on the mono out circuit.
  5. Test for less than 1 ohm between the X2 VCIM connector terminal 2 and the radio X2 connector terminal 15.
    6. ⇒If more than the specified value repair open or high resistance on the low reference circuit.
  6. If all circuits test normal, replace the VCIM.

Circuit/System Testing (Noisy OnStar® Audio)
  1. Ignition OFF, disconnect the X2 radio harness connector.
  2. Disconnect the X2 VCIM harness connector.
  3. Test for less than 1 volt between the X2 VCIM connector terminal 1 and the radio X2 connector terminal 7.
    4. ⇒If more than the specified value repair short to voltage on the mono out circuit.
  4. Test for less than 1 volt between the X2 VCIM connector terminal 2 and the radio X2 connector terminal 15.
    5. ⇒If more than the specified value repair short to voltage on the low reference circuit.
  5. Test for infinite resistance between the X2 VCIM connector terminal 1 and 2 and ground.
    6. ⇒If less than infinite resistance repair short to ground on the mono out circuit or low reference circuit.
  6. If all circuits test normal, replace the VCIM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Radio Antenna Base Replacement
    •  Control Module References for VCIM replacement, setup, and programming