Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

No OnStar® Audio

Ignition OFF, disconnect the X2 radio harness connector.
Ignition ON, test for a momentary AC voltage (OnStar® audio signal) between the X2 connector terminal cavity 7 and 15 when the white dot button on the keypad is pressed.
- If a momentary AC voltage was present replace the radio.
Ignition OFF, disconnect the X2 VCIM harness connector.
Test for less than 1 ohm between the X2 VCIM connector terminal 1 and the radio X2 connector terminal 7.
- If more than the specified value repair open or high resistance on the mono out circuit.
Test for less than 1 ohm between the X2 VCIM connector terminal 2 and the radio X2 connector terminal 15.
- If more than the specified value repair open or high resistance on the low reference circuit.
If all circuits test normal, replace the VCIM.

Noisy OnStar® Audio

Ignition OFF, disconnect the X2 radio harness connector.
Disconnect the X2 VCIM harness connector.
Test for less than 1 volt between the X2 VCIM connector terminal 1 and the radio X2 connector terminal 7.
- If more than the specified value repair short to voltage on the mono out circuit.
Test for less than 1 volt between the X2 VCIM connector terminal 2 and the radio X2 connector terminal 15.
- If more than the specified value repair short to voltage on the low reference circuit.
Test for infinite resistance between the X2 VCIM connector terminal 1 and 2 and ground.
- If less than infinite resistance repair short to ground on the mono out circuit or low reference circuit.
If all circuits test normal, replace the VCIM.