Engine Controls - Tests W/O Codes - Except Diesel: Introduction

Before diagnosing symptoms or intermittent faults, perform basic diagnostic procedures in appropriate BASIC DIAGNOSTIC PROCEDURES article and applicable self-diagnostic tests in appropriate SELF-DIAGNOSTICS article. 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 Powertrain Control Module (PCM). Check with manufacturer for latest PCM application.

Symptom checks 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 problems may cause a noticeable driveability problem or cause the Malfunction Indicator Light (MIL) to illuminate on some vehicles. These test procedures should also be used if a soft (intermittent) trouble code is present, but no problem is found during self-diagnostic testing.

NOTE: For specific testing procedures, see appropriate SELF-DIAGNOSTICS article. For specifications, see appropriate ON-VEHICLE ADJUSTMENTS and SERVICE & ADJUSTMENT SPECIFICATIONS articles.