Diagnostic Aids

Important: 

• Do not clear the DTC unless directed by a diagnostic procedure. Clearing the DTCs will erase all Freeze Frame and Failure Records stored in PCM memory.
• Poor engine performance can sometimes be diagnosed as a transmission driveability condition. In order to avoid mis-diagnosis of the automatic transmission, always perform DIAGNOSTIC SYSTEM CHECK -- ENGINE CONTROLS in Engine Controls.
• Use a scan tool that is known to function correctly. If necessary, test the scan tool on another vehicle.
• Ensure the scan tool contains the most current file available.
• The scan tool will display a loss of communication error message under the following conditions:
  • PCM power is interrupted
  • The ignition switch is turned OFF
  • The battery voltage level is very low
  • A poor connection at the diagnostic link connector (DLC)