Diagnostic Instructions
Circuit/System Description
The vehicle navigation radio and Onstar® system (If equipped) both utilize the cellular microphone located on the inside rearview mirror to receive voice commands. The navigation radio receives an audio voice signal from the communication interface
module (CIM). If the vehicle is not equipped with Onstar®, the microphone is connected only to the navigation radio.
Reference Information
Schematic Reference
Radio/Navigation System Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Radio/Audio System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, verify the OnStar® voice recognition is operating normally.
Circuit/System Testing
With UE1
- Ignition OFF, disconnect the X3 harness connector at the CIM.
- 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. |
- Ignition ON, test for less then 1 volt between the navigation voice low reference circuit terminal 4 and ground.
⇒ | If greater then specified range, test for a short to voltage. If the circuit tests normal, replace the radio. |
- 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 an open/high resistance. If the circuit tests normal, replace the radio. |
- Ignition ON, test for 8.5-9.5 volts between the navigation voice signal circuit terminal 2 and the ground.
⇒ | If less than specified range, test the drain wire circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio. |
- If all circuits test normal, replace the CIM.
Without UE1
- Ignition OFF, disconnect the harness connector at the inside rearview mirror.
- Ignition ON, test for 8.5-9.5 volts between the cellular microphone signal circuit terminal 10 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. |
- Ignition ON, test for less then 1 volt between the terminal 2 and ground.
⇒ | If greater then specified range, test for a short to voltage. If the circuit tests normal, replace the radio. |
- If all circuits test normal, replace the inside rearview mirror assembly.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.