Flow of Diagnosis

Flow Of Diagnosis:

1. Complete REPAIR HISTORY WORKSHEETS and DRIVEABILITY WORKSHEETS. Forms are located under Info Type - Technical/Management Support. Get a detailed description of the complaint. If necessary, verify condition by road testing.

2. Check TSB'S for manual updates, testing procedures, warranty and recall information. In many cases, TSB's contain valuable information found nowhere else.

3. Review Checking the Basics and perform thorough underhood inspection. Problems can frequently be resolved at this stage without further testing. Visually inspect the following:

^ Vacuum hoses for proper routing, tight connections, splits, kinks, obvious tampering.

NOTE: Some manufacturers use an orifice-insert within a vacuum line as a delay device. Do not mistake such a device for tampering and remove it.

^ Vacuum fittings for improperly capped or plugged ports. Be sure to check hidden areas around the throttle body and other components..
^ Ignition wires for proper routing, cracking, hardness, and tight connections at distributor, coil, and spark plugs.
^ Electrical wiring and harness connections for tight fit, abrasions, breaks, etc. Ground connections must be clean and tight.
^ Verify that components are properly installed and have not been modified or damaged. Ensure that any replaced components are correct for the application.
^ Check for air or vacuum leaks around intake and exhaust manifolds, throttle body, air flow meter, and air induction hoses.
^ Catalytic converter(s), muffler, exhaust pipes, brackets, and hangers for modification or damage.

4. If the Malfunction Indicator Light (MIL) indicates the presence of trouble codes, see Computers and Control Systems for information on extracting and reading codes.

5. If codes are not present, see Diagnosis by Symptom under the appropriate section for troubleshooting procedures related to particular driveability problems.

6. When the problem area has been defined, proceed to the specific section for more thorough diagnosis, testing, and repair information.