2003 Chevrolet Impala Owner's Manual - Page 202

Traffic Interrupt Feature: Your radio can interrupt the play of a cassette, CD, or XMTM, DAB station. or Press the TRAF button. The radio will seek to a station that broadcasts traffic announcements. When the radio finds a station that broadcasts traffic announcements, it will stop. TRAF will appear on the display. When a traffic announcement comes on the station that was found, you will hear it. When the traffic announcement is over, the radio will resume play of the cassette, CD, or XMTM, DAB station. If no or station is found, NO TRAF will appear on the display. Radio Messages CAL ERR (Calibration Error): This message is displayed when the radio has not been calibrated properly for the vehicle. You must return to the dealership for service. LOCKED: This message is displayed when the THEFTLOCK@system has locked up. You must return to the dealership for service. 3-79