Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform basic diagnostic procedures in BASIC TESTING article and self-diagnostics in TESTS W/CODES article. Use this article to diagnose driveability problems existing when a Diagnostic Trouble Code (DTC) is not present.

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 the 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 the 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 the SPECIFICATIONS article.