Engine Controls - Tests W/O Codes: Introduction

CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Before proceeding with basic diagnostic procedures, ensure testing procedure is followed, as some systems which may result in a no-start condition may cause a Diagnostic Trouble Codes (DTC) to be stored in the Powertrain Control Module (PCM). See DIAGNOSTIC PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.

If no-start condition still exists after checking and repairing all DTCs, perform a careful and complete visual inspection. Many problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. See VISUAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS. Before condemning the computerized system, perform each test listed in this article.

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 DTC code is present, but no problem is found during self-diagnostic testing.

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