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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 16 (Cellular, Entertainment, And Navigation System) >> Diagnostic Information and Procedures >> Unable to Contact OnStar Call Center >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.
  • The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 min after turning the ignition ON for the GPS satellites to acquire vehicle signal.
  1. Verify the OnStar Generation you are working on by using a scan tool under Selected Vehicle Configuration/Telematics Communication Interface Control Module. Failure to use the correct document will result in incorrect diagnoses.
  2. Ignition OFF and all vehicle systems OFF, disconnect the cellular GPS coax cable connector at the K73 Telematics Communication Interface Control Module. It may take up to 2 min for all vehicle systems to power down.
  3. Connect the EL-49903-1  Test Antenna, Navn-Cell Comn to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.
  4. Verify the DTC does not set while operating the vehicle within the conditions for running the DTC.
    • If the DTC sets 

      Replace the K73 Telematics Communications Interface Control Module.

    • Go to next step: If the DTC does not set 
  5. Ignition OFF.
  6. Disconnect the EL-49903-1  Test Antenna, Navn-Cell Comn from the K73 Telematics Communication Interface Control Module
  7. Disconnect the GPS and cellular coax cable connector at the T4G Cellular Phone, Navigation, and Digital Radio Antenna.

    Test the coax cable. Refer to Component Testing.

  8. Test the coax cable between the K73 Telematics Communication Interface Control Module and the T4G Cellular Phone, Navigation, and Digital Radio Antenna. Refer to Component Testing.
    • If the coax cable does not pass the test 

      Replace the coax cable.

    • Go to next step: If the coax cable passes the test 
  9. Test or replace the T4G Cellular Phone, Navigation, and Digital Radio Antenna.
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