Chevrolet 2003 Impala Owner's Manual page 192

Traffic Interrupt Feature: Your radio can interrupt the
play of a CD, or XMTM, or DAB station. 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 CD, or XMTM, or
DAB station. If no 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.
If any error occurs repeatedly or if an error can't be
corrected, contact your dealer.
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