Using Scan Tool
WARNING: This page is about a different car, the 1994 Cadillac Fleetwood. However, it is still accessible from the selected car via links, so may be relevant.
During normal operation, the Powertrain Control Module (PCM) acts as a master for the serial data and procures DTCs from other vehicle control modules. During scan tool usage, scan tool will act as the master and DTCs will displayed from vehicle control modules. Current DTCs will be displayed on scan tool with a "C" immediately following the DTC. History DTCs will be displayed on scan tool with an, "H" immediately following the DTC. Refer to scan tool operators manual for further information on scan tool usage.