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Symptoms - Cellular Communication: Notes

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2004 GMC Yukon XL, 2004 GMC Yukon, 2004 Chevrolet Tahoe, 2004 Chevrolet Suburban, and 2004 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: The following steps must be completed before using the symptom tables.
  1. Perform the Diagnostic System Check - Cellular Communication  before using the Symptom Tables in order to verify that all of the following are true:
    • There are no DTCs set.
    • The control module can communicate via the serial data link.
  2. Review the system operation in order to familiarize yourself with the system functions. Refer to OnStar Description and Operation .
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