Circuit/System Testing

OnStar Malfunction without Navigation Radio

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. See Special Tools .
3. Ignition ON, wait 5 minutes, then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, ask 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.
4. 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.
5. If all circuits test normal, replace the T4E cellular phone and navigation antenna.

OnStar Malfunction with Navigation Radio

1. Ignition OFF, disconnect both the GPS and cell coax cable connector 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. See Special Tools .
3. Ignition ON, wait 5 minutes, then contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, ask the consultant to verify the vehicle location to confirm the GPS system is functioning.
   • If the OnStar system does not function, replace the k73 telematics communication interface module.
4. Ignition OFF, connect both coax cable connectors to the K73 telematics communication interface control module.
5. Disconnect the GPS coax cable connector at the navigation antenna signal splitter. Connect the EL-49903  to the navigation antenna signal splitter. See Special Tools .
6. Ignition ON, wait 5 minutes, contact the OnStar call center consultant by pressing the blue OnStar button. A call center consultant should answer the call, ask the consultant to verify the vehicle location to confirm the GPS system is functioning.
   • If the OnStar GPS does not function, perform the coax cable test on the coax cable between the K73 telematics communication interface control module and the navigation antenna signal splitter, refer to Component Testing. If the cable tests normal replace the navigation antenna signal splitter.
7. Ignition OFF, perform the coax cable test on the coax cable between the navigation antenna signal splitter and the T4E cellular phone and navigation antenna, refer to Component Testing. The coax cable should pass the test.
   • If the coax cable does not pass the test, replace the coax cable.
8. If all circuits test normal, replace the T4E cellular phone and navigation antenna.

Navigation Radio Malfunction

1. Ignition OFF, disconnect the GPS coax cable connector at the navigation radio.
2. Connect the EL-49903  to the navigation radio; place the test antenna on the roof of the vehicle. See Special Tools .
3. Verify the Navigation Radio functions while driving the vehicle.
   • If the navigation radio does not function, replace the navigation radio.
4. Ignition OFF, perform the coax cable test on the coax cable between the navigation radio and the navigation antenna signal splitter, refer to Component Testing. The coax cable should pass the test.
   • If the coax cable does not pass the test, replace the T4E cellular phone and navigation antenna coax.
5. If all circuits test normal, replace the navigation antenna signal splitter.