Circuit/System Testing (with Navigation Radio)

WARNING: This page is about a different car, the 2012 Buick Verano. 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 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 communications 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 communications interface control module. Place the test antenna on the roof of the vehicle, ignition ON.
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.
- If the DTC does not set
Ignition OFF, connect the coax cable to the K73 telematics communications interface control module and disconnect the coax cable from the T15 navigation signal splitter, ignition ON.
Test for 4.5-5.5 V between the coax cable center conductor and the outer shield.
- If greater than 5.5 V
  Test or replace the coax cable.
- If less than 4.5 V
  Test or replace the coax cable.
- If between 4.5-5.5 V
Ignition OFF.
Test the coax cable between the T15 navigation signal splitter and the T4G cellular phone, navigation, and digital radio antenna. Refer to Component Testing below.
- If the coax cable does not pass the test
  Replace the coax cable.
- If the coax cable passes the test
Test or replace the T15 navigation and signal splitter.