Serial Data
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2003 Hummer H2, 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 GMC Sierra, and 2003 GMC Savana. 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 special scan tool. Access serial data by connecting a scan tool to DLC. Update intervals and information contained within data stream vary with model application.