Turn Signal On
WARNING: This page is about a different car, the 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, 2001 Chevrolet Monte Carlo, and 2001 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
Radio activates turn signal on audible warning as requested by Body Control Module (BCM). BCM sends a class 2 message to radio indicating chime frequency of a fast rate and at a duration 2 seconds.