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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis (Single Page) >> External Pages >> Different car >> Section 1038 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> No (or Noisy) OnStar Audio >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X2 harness connector at the CIM.
  2. Ignition ON, test for less than 5 mV AC between the signal circuit terminal 1 and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
  3. Install a DMM between the signal circuit terminal 1 and ground. Set the DMM to capture AC voltage using the MIN MAX function.
  4. Press the voice recognition button. Verify the DMM captured greater than 20 mV AC.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  5. Install a DMM between the signal circuit terminal 1 and the low reference circuit terminal 2. Set the DMM to capture AC voltage using the MIN MAX function.
  6. Press the voice recognition button. Verify the DMM captured greater than 20 mV AC.
    • If less than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the radio.
  7. If all circuits test normal, replace the CIM.
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