Class 2 Serial Data Line
WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Chevrolet Cavalier, 2001 Pontiac Sunfire, and 2001 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The class 2 serial data line is a Purple wire connected between Data Link Connector (DLC) terminal No. 2 and Body Control Module (BCM), Electronic Brake Control Module (EBCM), Instrument Panel Cluster (IPC), Powertrain Control Module (PCM), Sensing and Diagnostic Module (SDM) and radio. Class 2 serial data line allows these modules to communicate with each other and with scan tool for diagnostic and testing purposes.