Engine Controls - Basic Diagnostic Procedures - 4-Cylinder: Introduction

NOTE: On Camry, Camry Solara, Highlander, MR2, Prius and RAV4, an engine immobilizer system may be used. Engine immobilizer system is a theft deterrent system which disables the engine from starting by not allowing ignition system operation and fuel injector operation unless proper ignition key is used. Models equipped with engine immobilizer system may be identified by looking at the ignition key. On models equipped with engine immobilizer system the top of the ignition key is thicker than a standard ignition key, as a transponder chip is incorporated into the top of the ignition key. For additional information on system operation and testing, see appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.

Before proceeding with basic diagnostic service procedures, ensure testing procedure is followed, as some systems which may result in a no-start condition may cause a Diagnostic Trouble Code (DTC) to be stored in the engine control module (ECM). See TESTING 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. Before condemning the computerized system, perform each test listed in this article.

NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.