Circuit/System Testing

Ignition OFF and vehicle systems OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module, ignition ON.
Test for less than 4 V between the signal circuit terminal 1 and ground
- If 4 V or greater
1. Ignition OFF, disconnect the X1 harness connector at the A11 Radio, ignition ON.
2. Test for less than 1 V between the signal circuits and ground.
  - If greater than 1 V, repair the short to voltage in the circuit.
  - If less then 1 V, replace the A11 Radio.
- If less than 4 V
Test for less than 4 V between the signal circuit terminal 2 and ground
- If 4 V or greater
1. Ignition OFF, disconnect the X1 harness connector at the A11 Radio, ignition ON.
2. Test for less than 1 V between the signal circuits and ground.
  - If greater than 1 V, repair the short to voltage in the circuit.
  - If less then 1 V, replace the A11 Radio.
- If less than 4 V
Ignition OFF.
Test for infinite resistance between the signal circuit terminal 1 and ground
- If less than infinite resistance
  Repair the short to ground on the circuit.
- If infinite resistance
Test for infinite resistance between the signal circuit terminal 2 and ground
- If less than infinite resistance
  Repair the short to ground on the circuit.
- If infinite resistance
Disconnect the X1 harness connector at the A11 Radio.
Test for less than 2 Ω in the signal circuit terminal 1.
- If 2 Ω or greater
  Repair the open/high resistance in the circuit.
- If less than 2 Ω
Test for less than 2 Ω in the signal circuit terminal 2.
- If 2 Ω or greater
  Repair the open/high resistance in the circuit.
- If less than 2 Ω
Replace the K73 Telematics Communication Interface Control Module.
Verify that the Connecting to OnStar® message is heard clearly through the audio system when the OnStar® blue button is pressed.
- If audio is not heard clearly
  Replace the A11 radio.
- If audio is heard clearly
All OK.