GM Service Manual Online
For 1990-2009 cars only

Important: The following steps must be completed before using the symptom tables.

  1. Perform the Diagnostic System Check - Vehicle. Before using the Symptom Tables, verify that all of the following are true:
  2. • There are no DTCs set.
    • The control module can communicate via the serial data link.
  3. Review the system operation in order to familiarize yourself with the system functions. Refer to OnStar Description and Operation .
  4. Perform the OnStar Symptom Diagnosis . This symptom table will enable the user to verify the customer complaint and narrow it to its source.

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the system. Refer to Checking Aftermarket Accessories.
    • Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    •  OnStar One or More Buttons Inoperative
    •  OnStar Call Center Remote Function Requests Inoperative
    •  OnStar Microphone Inoperative - Caller Cannot Be Heard
    •  OnStar Steering Wheel Control Functions Inoperative
    •  OnStar Button LED Inoperative
    •  No (or Noisy) OnStar Audio
    •  OnStar Global Positioning System (GPS) Data Not Current or Inaccurate