General System Description

Diagnostic Chart:

This is the starting point for the diagnostic procedures. The diagnostic charts are related to the Engine Control Module (ECM) and will determine if the ECM is working properly.

This section diagnoses the fuel system controlled by the ECM and has charts to diagnosis a circuit when the ECM has displayed a trouble code.

The way to approach a problem is to follow some basic steps.

1. Are the On-Vehicle Diagnostics working?

We find this out by performing the "On-Board Diagnostic System Check" Since this is the starting point for the diagnostic procedure, always begin here.

If the On-Vehicle Diagnostics aren't working, the "On-Board Diagnostic System Check" will lead you to an "A - Chart" to correct the problem. A - Charts

If the On-Vehicle Diagnostics are OK, the next step is:

2. Is there a Trouble Code stored?

If a trouble code is stored, go directly to the numbered DTC chart in Diagnostic Charts / Trouble Code Descriptions. This will determine if the fault is still present. Engine Control System

If no trouble code is stored, the third step is:

3. "Scan Tool" Serial Data.

This involves reading the various pieces of information available on the Serial Data Stream with one of the tools available for that purpose. Information on the meaning of the various displays and expected readings can be found in Normal Scan Data Values. Scan Tool Testing and Procedures

This procedure, which takes only a short time, will help lead you to repair the problem in the least amount of time.