Circuit/System Testing

Verify the OnStar® voice recognition is operating normally.
- If the OnStar® voice recognition is inoperative, refer to OnStar Microphone Inoperative - Caller Cannot Be Heard .
Ignition OFF, disconnect the radio harness connector X1 and VCIM harness connector X3.
Test for less than 1 volt on the microphone out circuit radio harness connector terminal 4 and ground.
- If greater than specified value, repair short to voltage.
Test for greater than 1 ohm between the microphone out circuit radio harness connector terminal 4 and ground.
- If less than specified value, repair short to ground.
Test for less than 1 ohm between the microphone out circuit radio harness connector terminal 4 and the microphone out signal circuit VCIM harness connector terminal 2.
If greater than specified value, repair open circuit.
Test for less than 1 volt on the low reference circuit radio harness connector terminal 5 and ground.
- If greater than specified value, repair short to voltage.
Test for greater than 1 ohm between the low reference circuit radio harness connector terminal 5 and ground.
- If less than specified value, repair short to ground.
Test for less than 1 ohm between the low reference circuit radio harness connector terminal 5 and the low reference signal circuit VCIM harness connector terminal 4.
- If greater than specified value, repair open circuit.
If all circuits test normal, replace the radio.