Tests W/O Codes: Introduction

Before attempting to diagnose symptoms or intermittent faults, ensure steps in BASIC TESTING have been performed. Use this article to diagnose driveability problems that exist when an obvious fault is not present.

Symptom checks are intended to direct the technician to malfunctioning component(s) so that further diagnosis may be performed. A "symptom" should lead to further testing of specific components or systems, or verification of adjustment specifications.

Use intermittent test procedures to locate intermittent driveability problems that do not occur when the vehicle is being tested. These problems may cause a noticeable driveability problem or cause the "malfunction" warning light to illuminate on some vehicles.

It is also possible that certain driveability concerns have been rectified by the manufacturer through substitution of a revised control unit. Check with manufacturer for latest information on updated components and control units.

NOTE: For specific component or system test procedures, refer to the SYSTEM/COMPONENT TESTS article. For tune-up specifications, refer to the SPECIFICATIONS article. For adjustment procedures, see the ADJUSTMENTS article.