Circuit/System Testing

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.

Ignition OFF and all vehicle systems OFF, disconnect the violet primary cellular 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.
Using the EL-49903-1 GM OnStar® test antenna connect the violet coax cable to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.
Verify the DTC does not set or a call can be completed to the OnStar® Call Center while operating the vehicle within the conditions for the fault.
- If the DTC sets or a call can not be completed to the OnStar® Call Center
  Replace the K73 Telematics Communications Interface Control Module.
- If the DTC does not set or a call can be completed to the OnStar® Call Center
Ignition OFF.
Disconnect the EL-49903-1 GM OnStar® test antenna from the K73 Telematics Communication Interface Control Module
Test the coax cable. Refer to Component Testing .
- If the coax cable does not pass the test
  Replace the coax cable.
- If the coax cable passes the test
Test or replace the T4D Cellular Phone and GPS Antenna.