Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform steps in BASIC TESTING and appropriate TESTS W/CODES . Use this article to diagnose driveability problems that exit when a hard fault code is NOT found, or on vehicle NOT equipped with a self-diagnostic system.

NOTE: Computer control unit have been revised to correct certain driveability problems. Check with manufacturer for latest computer application.

Symptom checks are intended to direct the technician to malfunctioning component(s) so further diagnosis may be performed. A symptom should lead to specific component or system testing, or an adjustment specification.

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 testing procedures, see SYSTEM/COMPONENT TESTS article. For specifications, see ADJUSTMENTS or SPECIFICATIONS article.