WARNING: This page is about a different car, the 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Locating Alternative Fuels Engine Control Module (AF ECM), Other CNG Engine Control Components & Harness Connectors
Courtesy of GENERAL MOTORS CORP.
Fig 2: Locating Camshaft & Crankshaft Position Sensors
Courtesy of GENERAL MOTORS CORP.
Fig 3: Locating ECT Sensor
Courtesy of GENERAL MOTORS CORP.
Fig 4: Locating Gas Mass Sensor/Mixture Control Valve Assembly & Other CNG Fuel System Components