Diagnostic Procedure
The diagnostic procedures used in this article are designed to find and repair engine performance related problems. The general approach is solving a problem with four basic steps shown in Fig 1 and described below:
- Are Diagnostics Working Properly?
Use the "PFI SYSTEM CHECK ". This is the starting point for the diagnostic procedure, always begin here. If the Diagnostics are not working properly, the "PFI System Check" will lead you to a chart to correct this condition. If the engine will not start or stalls , see PFI CHART A-3: NO START OR STALL AFTER START . If the diagnostics are working, the next step is: - Are Troubles Code Displayed?
If a trouble code is identified by diagnostics, the "PFI SYSTEM CHECK " which will direct you to the appropriate chart. Refer to "TROUBLE CODE DISPLAY " later in this article for the correct procedure to display trouble codes. If no trouble codes are stored, the next step is: - Do All Input Test Pass?
If a switched input to the PCM is not indicating the proper status and change of state, DIAGNOSTIC TESTS should be referenced for diagnosis. If all switched inputs are operating correctly, the next step is: - Is The Fuel Control System Working Correctly?
The "PFI SYSTEM CHECK " will be used to correct the problem. If the "PFI System Check" shows that the system is in closed loop and operating normally, go to TROUBLE SHOOTING - NO CODES article.