- Important Preliminary Checks

BEFORE USING THIS SECTION
Before using this section you should have performed the On-Board Diagnostic System Check and determined that:
1. The control module and MIL (Service Engine Soon) are operating correctly.
2. There are no diagnostic trouble codes stored, or there is a diagnostic code but no MIL (Service Engine Soon).
^ Several of the following symptom procedures call for a careful visual/physical check.
- The importance of visual/physical checks cannot be over stressed, because they can lead to correcting a problem without further checks and can save valuable time.

BEFORE STARTING
This check should include:
^ Control module grounds for being clean, tight, and in their proper location.
^ Vacuum hoses for splits, kinks and proper connections, as shown on "Vehicle Emission Control Information" label. Check thoroughly for any type of leak or restriction.
^ Air leaks at all mounting areas of the intake manifold sealing surfaces.
^ Ignition wires for cracking, hardness, proper routing, or carbon tracking.
^ Wiring for proper connections, pinches, and cuts.
^ The following symptom charts contain groups of possible causes for each symptom and cover several engines.

NOTE: These procedures are not necessarily meant to be done in consecutive order.

If TECH 1 scan tool readings do not indicate the problems, then proceed in a logical order, easiest to check or most likely cause first. To determine if a particular system or component is used on a specific vehicle, refer to the Engine Control Module/Diagrams.
Diagrams

SYMPTOM
Verify the customer complaint, and locate the correct symptom in the table of contents. Check the items indicated under that symptom.