Circuit/System Testing

WARNING: This page is about a different car, the 2018 Buick Envision. 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.

Ignition OFF/Vehicle 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 Test Antenna Navn-Cell Comn 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/vehicle in Service Mode.
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 running the DTC.
- If the DTC sets or a call can not be completed to the OnStar Call Center
  Replace the K73 Telematics Communications Interface Control Module.
- Go to next step: If the DTC does not set or a call can be completed to the OnStar Call Center
Ignition OFF/Vehicle OFF.
Disconnect the EL-49903-1 Test Antenna Navn-Cell Comn 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.
- Go to next step: If the coax cable passes the test
Test or replace the T2RR Antenna - Roof Rear.