2004 GMC Sierra 1500 Pickup Owner's Manual - Page 258

If the current tuned station does not broadcast traffic announcements, press this button and the radio will seek to a station that does. When the radio finds a station that broadcasts traffic announcements, it will stop and TRAF will be displayed. When a traffic announcement comes on the tuned radio station you will hear it. If no station is found, NO TRAFFIC will appear on the display. If TRAF is on the display you can press the TRAF button to turn off the traffic announcements. Your radio will play the traffic announcement even if the volume is low. Your radio will interrupt the play of a cassette tape or CD if the last tuned station broadcasts traffic announcements. This function does not apply to XM™ Satellite Radio Service. Radio Messages CAL ERR (Calibration Error): Your audio system has been calibrated for your vehicle from the factory. If CAL ERR appears on the display, it means that your radio has not been configured properly for the vehicle and must be returned to the dealer for service. LOCKED: This message is displayed when the THEFTLOCK® system has locked up. You must return to the dealer for service. XM™ Radio Messages Radio Display Message XL (Explicit Language Channels) Condition XL on the radio display, after the channel name, indicates content with explicit language. Updating encryption code Loss of signal Action Required These channels, or any others, can be blocked at a customer's request, by calling 1-800-852-XMXM (9696). Updating The encryption code in your receiver is being updated, and no action is required. This process should take no longer than 30 seconds. Your system is functioning correctly, but you are in a location that is blocking the XM signal. When you move into an open area, the signal should return. No Signal 3-94