Engine Controls - Trouble Shooting - No Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform steps in BASIC DIAGNOSTIC PROCEDURES and appropriate SELF-DIAGNOSTICS articles. 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 Engine Control Module (ECM) or Powertrain Control Module (PCM). Check with manufacturer for latest ECM/PCM.

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 an intermittent DTC was present, but no problem was found during self-diagnostic testing.

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