Circuit/System Testing (without Navigation Radio)

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 minutes after turning the ignition ON for the GPS satellites to acquire vehicle signal.

Ignition OFF and all vehicle systems OFF, disconnect the GPS and cellular coax cable connector at the K73 telematics communication interface control module. It may take up to 2 minutes for all vehicle systems to power down.
Using the EL-49903-3 kit (EL-49903-5 adapter and EL-49903-4 coax cable), connect the EL-49903 GM OnStar antenna diagnostic tool kit to the K73 telematics communication interface control module. Place the test antenna on the roof of the vehicle.
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 communication interface control module.
- If the DTC does not set
Ignition OFF.
Disconnect the EL-49903 GM OnStar antenna diagnostic tool kit from the K73 telematics communication interface control module
- If the coax cable does not pass the test
  Replace the coax cable.
- If the coax cable passes the test
Test or replace the T4G cellular phone, navigation, and digital radio antenna.