Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform Basic Diagnostic Procedures in the BASIC TESTING article and Self-Diagnostic Tests in the TESTS W/CODES article. Use this article to diagnose driveability problems existing when a hard fault code is not present. The items listed in this article will not cause MIL to come on or store codes in PCM memory.

NOTE: Some driveability problems may have been corrected by manufacturer with a revised computer control unit. Check with manufacturer for latest computer application.

Symptom checks can direct technician to malfunctioning component(s) for further diagnosis. A symptom should lead to a specific component, system test, or adjustment.

Use intermittent test procedures to locate driveability problems that do not occur when vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present but no problem was found during self-diagnostic testing.

NOTE: For specific test procedures, see SYSTEM/COMPONENT TESTS article. For specifications, see the ADJUSTMENTS or SPECIFICATIONS article.