How To Use This Article

This portion of the article is to be used only AFTER you have checked that:

• The On-Car Diagnostics are working.
• The ECM and "SERVICE ENGINE SOON" light are operating.
• There are no trouble codes stored, or only intermittent ones.
• The fuel control system is operating properly, by performing the System Performance Check.
• A careful visual check found no obvious problems.

Verify the customer complaint, and locate the correct symptom below. Check the items indicated under that symptom. These procedures will normally lead you to a component system on the vehicle, such as EGR, EST, TCC, etc. These are covered in the Component System charts. These charts are listed with a "C" before the number of the chart (C-2A, for example).