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Circuit/System Testing

  1. Ignition OFF, disconnect the cellular antenna coax from the CIM module and the cellular antenna.
  2. Ignition ON, test for less than 1 volt between the antenna coax center terminal and ground.
    • If greater than the specified range, replace the antenna coax.
  3. Ignition ON, test for less than 1 volt between the antenna coax outer shield and ground.
    • If greater than the specified range, replace the antenna coax.
  4. Test for infinite resistance between the antenna coax center terminal and ground.
    • If less than the specified value, replace the antenna coax.
  5. Test for infinite resistance between the antenna coax outer shield and ground.
    • If less than the specified value, replace the antenna coax.
  6. Test for less than 5 ohms at the cellular antenna coax center terminal from end to end.
    • If greater than specified value, replace the cellular antenna coax cable.
  7. Test for less than 5 ohms at the cellular antenna coax outer shield from end to end.
    • If greater than specified value, replace the cellular antenna coax cable.
  8. Test for infinite resistance between the antenna coax center terminal and the outer shield.
    • If less than specified value, replace the cellular antenna coax cable.
  9. If coax cable tests normal, replace the cellular antenna.
  10. Press the OnStar® Call Center button. Verify the system connects to OnStar® call center.
    • If a connection is not made to the OnStar® call center, replace the CIM.
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