- Important Preliminary Checks

DIAGNOSTIC NOTES
Diagnostics Charts
The charts in this section indicate what subsystems and components should be checked. These charts are not meant to be component replacement lists. Each subsystem or component should be checked for proper operation and repaired or replaced only if they are not operating properly.

Selecting Appropriate Chart
Select the symptom with the description that best fits the customer complaint. Then begin performing the tests suggested and proceed until the root cause is found. The suggested tests are generally listed in order of probability and/or ease of diagnosis. The tests need not be performed in the listed order though. If you have already performed one of the tests listed, there is no need to perform it a second time.

Preconditioning Vehicle
It is essential that the vehicle has been properly warmed up and is at operating temperature, except when attempting to diagnose a no start or cold driveablity problem. The catalytic converter and feedback system will not function as designed if this is not achieved. Failure to do so will result in inaccurate test results.

PRELIMINARY VISUAL CHECKS
^ Vacuum hoses for splits, kinks and proper connections. 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, harness, proper routing, arcing and carbon tracking.

^ Wiring for proper connections, pinches, and cuts.

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

^ Harnesses for proper routing.

ORDER OF DIAGNOSTICS
If on-board diagnostic readings DO NOT indicate a problem, then proceed in a logical order starting with the easiest to check or the most likely cause first.