• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Cellular Telephone Voice Signal | 1 | 1 | 1 | -- |
Cellular Telephone Voice Low Reference | -- | 1 | -- | -- |
1. No (or Noisy) OnStar® Audio |
When an OnStar® keypress is made, a serial data message is sent to the audio system to mute all radio functions and output OnStar® originated audio. After the audio system is muted, the communication interface module (CIM) transmits signals to the audio system on the cellular telephone voice signal and cellular telephone voice low reference circuits.
OnStar Description and Operation
Control Module References for scan tool information
⇒ | If audio is not heard clearly, refer to Speaker Malfunction. |
⇒ | If OnStar® message is noisy or distorted, refer to Circuit/System Testing. |
• | Audio Signal Circuit- terminal 7 |
• | Audio Common Circuit- terminal 15 |
⇒ | If AC voltage was not present, test the circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the CIM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for radio or CIM replacement, setup, and programming.