- Important Preliminary Checks

IMPORTANT PRELIMINARY CHECKS
^ Before using Diagnosis by Symptom you should have performed the On-Board Diagnostic System Check. Testing and Inspection

^ Verify the customer complaint, and locate the correct symptom. Check the items indicated under that symptom.

^ If the engine cranks but will not run, refer to Chart A-3 Engine Cranks But Will Not Run. Related Tests, Information and Procedures

^ Several of the symptom procedures call for a careful visual and physical checks. The importance of this step cannot be stressed too strongly - it can lead to correcting a problem without further checks and can save valuable time.

BEFORE STARTING
This check should include:

^ Engine Control Module (ECM) grounds for being clean, tight, and in their proper location.

^ Vacuum hoses for splits, kinks, and proper connections, as shown on underhood "Vehicle Emission Control Information" label. Check thoroughly for any type of leak or restriction.

^ Air leaks at throttle body mounting area and intake manifold sealing surfaces.

^ Ignition wires for cracking, hardness, proper routing, and carbon tracking.

^ Wiring for proper connections, pinches, and cuts.

If wiring harness or connector repair is necessary, refer to Diagrams/Diagnostic Aids for correct procedure. Diagnostic Aids

^ The symptoms listed under Diagnosis By Symptom cover several engines. To determine if a particular system or component is used, refer to Diagrams/Electrical/ECM for application. Diagrams