Engine Controls - Tests W/O Codes: Introduction

NOTE: For specific testing procedures, see the I - SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section. For specifications, see the ADJUSTMENTS or SPECIFICATIONS article in the ENGINE PERFORMANCE section.

Before diagnosing symptoms or intermittent faults, perform steps in BASIC TESTING and TESTS W/CODES articles in the ENGINE PERFORMANCE section. Use this article to diagnose driveability problems existing when a hard fault code is not present.

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

Symptom checks can direct the technician to malfunctioning components for further diagnosis. A symptom should lead to a specific component test, 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.

The recommended procedures for each symptom will be indicated by numbers from one to 28 (and may also contain specific instructions related to that number). See SYMPTOM PROCEDURE DEFINITION. Not all recommended procedures apply to all vehicles.