Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform Basic Diagnostic Procedures in the BASIC TESTING article and Self-Diagnostics steps in the TESTS W/CODES article. Use this article to diagnose driveability problems existing when a hard fault code is not present (MIL has not illuminated).

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