How To Use This Article

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

• The On-Car Diagnostics are working.
• No trouble codes are stored, or only intermittent ones.
• Ensure that fuel control system is operating properly.
• Ensure that "Field Service Mode Check" of "DFI System Check" found no problems. Refer to the DFI ECM TESTS/CODES (all models) and/or DFI BCM TESTS/CODES (DeVille & FWD Fleetwood) article in this section.
• Ensure that a careful visual check found no obvious problems.

Verify the customer's 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.