- Important Preliminary Checks

Before using this section, you should have performed the On-Board Diagnostic System Check and determined that: Testing and Inspection

1. The Control Module and Malfunction Indicator Lamp (MIL) are operating correctly.
2. There are no Diagnostic Trouble Codes (DTCs) stored, or a DTC exists but without a MIL.

Several of the following symptom procedures call for a careful visual and physical check. The visual and physical checks are very important. The checks can lead to correcting a problem without further checks which may save valuable time.

Visual and Physical Checks

^ Check the Control Module grounds for being clean, tight and in their proper location.
^ Check the vacuum hoses for splits, kinks and proper connections, as shown on the Vehicle Emission Control Information label.
^ Check thoroughly for any type of leak or restriction.
^ Check for air leaks at all the mounting areas of the intake manifold sealing surfaces.
^ Check the ignition wires for the following conditions:

- Cracking
- Hardness
- Proper routing
- Carbon tracking

^ Check the wiring for the following items:

- Proper connections
- Pinches
- Cuts

^ The following symptom tables contain groups of possible causes for each symptom and cover several engines. The following symptom tables cover several engines. The order of these procedures is not important. If the scan tool readings do not indicate the problems, then proceed in a logical order, easiest to check or most likely to cause first. In order to determine if a specific vehicle is using a particular system or component, refer to the Wiring Diagrams for an application.

Symptom

^ Verify the customer complaint.
^ Locate the correct symptom table. Check the items indicated under that symptom.