Engine Controls - Tests W/O Codes: Introduction

NOTE: For trouble shooting with no codes information on Passport, refer to Rodeo in Isuzu TROUBLE SHOOTING - NO CODES article.

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

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 a soft (intermittent) trouble code was present, but no problem was found during self-diagnostic testing.

NOTE: For specific testing procedures, see SYSTEM & COMPONENT TESTING article. For specifications, see ON-VEHICLE ADJUSTMENTS article or SERVICE & ADJUSTMENT SPECIFICATIONS article.