Schematic Reference

OnStar Schematics

Connector End View Reference

Entertainment/Communication Connector End Views

Electrical Information Reference

Ignition ON, verify the OnStar® voice recognition is operating normally.

1. Ignition OFF, disconnect the C3 harness connector at the CIM.
2. Ignition ON, test for 8.5-9.5 volts between the navigation voice signal circuit terminal 2 and ground.

⇒	If less than specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.

⇒	If greater than specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.

3. Ignition OFF, test for less than 10 ohms between the navigation voice low reference circuit terminal 4 and ground.

⇒	If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the radio.

4. Ignition ON, test for 8.5-9.5 volts between the navigation voice signal circuit terminal 2 and the drain wire circuit terminal 5.

⇒	If less than specified range, test the drain wire circuit for a short to voltage or an open/high resistance.

5. Ignition OFF, disconnect the C1 harness connector at the radio.
6. Verify that a test lamp does not illuminate between B+ and the navigation voice low reference circuit terminal 5.

⇒	If the test lamp illuminates, test the low reference circuit for a short to ground.

7. If all circuits test normal, replace the CIM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio replacement, setup, and programming