Symptoms - Cellular Communication: Intermittent
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING WIRING SYSTEMS FOR INTERMITTENT & POOR CONNECTIONS in Wiring Systems.