Key-In-Ignition Warning
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2003 GMC Savana Special, 2003 GMC Savana Camper Special, 2003 GMC Savana, 2003 Chevrolet RV Cutaway, and 2003 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
The BCM sends a class 2 message to the radio or the chime module (UL5 RPO code) to activate the key-in-ignition audible warning when the BCM detects that the key is in the ignition with the driver door open. The key-in-ignition chime sounds at the medium rate of 150 pulses per minute until the driver door is closed or the key is removed from the ignition switch.