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Home >> Hummer >> 2008 >> H3 Base, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 491 (Cellular System, Entertainment System And Navigation System) >> Diagnostic Information and Procedures >> Unable to Contact OnStar Call Center >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect both the GPS and cell coax cable connectors at the K73 telematics communication interface control module.
  2. Connect the EL-49903  to the K73 telematics communication interface control module, place the test antenna on the roof of the vehicle.
  3. Ignition ON, wait 5 minutes, and then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call.
    • If the unit does not connect to the OnStar Call Center and the subscription is valid, use a scan tool to obtain and record the following information: Electronic Serial Number (ESN), Station Identifier (STID), GM 8-digit part number, Mobile Identification Number (MIN), Mobile Dialed Number (MDN), Transceiver ID (Trans ID) and call GM TAC.
  4. Request the consultant to verify the vehicle location to confirm the GPS system is functioning.
    • If the OnStar GPS does not function, replace the K73 telematics communication interface module.
  5. Ignition OFF, perform the coax cable test on the coax cable, refer to Component Testing. The coax cable should pass the test.
    • If the coax cable does not pass the test, replace the coax cable.
  6. If all circuits test normal, replace the T4 cellular phone and navigation antenna.
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