Diagnostic System

The ECM of the GMCCS is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, the ECM lights the "CHECK ENGINE" light located on instrument panel.

Fig 1: Identification of ECU Electrical Connector

Fig 2: GMCCS Component Locations

Fig 3: ECM Wiring Connector Voltage

Fig 4: Example of Normal Operation Code Output

Fig 5: Example of Trouble Code Output