Serial Data
WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
PCM has a serial data line. Serial data is a stream of electrical impulses which can be exchanged between control modules. Serial data can be interpreted using a scan tool. Access serial data by connecting a scan tool to Data Link Connector (DLC). Update intervals and information contained within data stream vary with model application.