A Preliminary Information - Cellular Communication

IMPORTANT:
1. Perform A Diagnostic System Check - Cellular Telephone before using the Symptom Tables in order to verify that all of the following are true:
^ There are no DTCs set.
^ The control module(s) can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to Cellular Telephone Operation.

VISUAL/PHYSICAL INSPECTION
^ Inspect for aftermarket devices which could affect the operation of the power windows, power door locks, or power mirrors.
^ 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 and Poor Connections in Diagrams.

SYMPTOM LIST
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
^ Cellular Telephone Inoperative
^ Cellular Telephone - Hands Free Operation Inoperative
^ Cellular Telephone - Voice Inoperative During Hands-Free
^ Cellular Telephone - Audio Inoperative During Hands-Free
^ Cellular Telephone - Noisy Audio During Hands-Free
^ OnStar(R) Will Not Power Up
^ OnStar(R) One or More Buttons Inoperative
^ OnStar(R) Call Center Horn Command Inoperative
^ OnStar(R) Call Center Exterior Lamp Command Inoperative
^ OnStar(R) Call Center Lock/Unlock Commands Inoperative
^ Unable to Contact OnStar(R) Call Center
^ OnStar(R) Call Center Unable to Configure OnStar(R) System
^ OnStar(R) Call Center Unable to Locate Vehicle
^ OnStar(R) Operator Unable to Hear Caller
^ OnStar(R) Button LED Inoperative
^ No OnStar(R) Audio