Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform preliminary inspection and self-diagnostic steps in TESTS W/CODES article. Use this article to diagnose driveability problems existing when a hard trouble code is not present.

NOTE: Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or Powertrain Control Module (PCM). Check with manufacturer for latest chip or 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. See SYMPTOMS .

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. See INTERMITTENTS .

NOTE: For specific testing, see SYSTEM/COMPONENT TESTS article. For specifications, see the ADJUSTMENTS article or the SPECIFICATIONS article.