Powertrain Control Module
WARNING: This page is about a different car, the 2002 Chevrolet Monte Carlo and 2002 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
These models use the Service Programming System (SPS) to reprogram the PCM and other modules. The SPS allows a technician to program a control module through the Data Link Connector (DLC). See POWERTRAIN CONTROL MODULE for 3.4L engines or POWERTRAIN CONTROL MODULE for 3.8L engines under PROGRAMMING in appropriate SELF-DIAGNOSTICS article in FAULT ISOLATION in ENGINE PERFORMANCE.