Engine Controls - System & Component Testing - 4-Cylinder: Introduction

NOTE: References to California models apply to California emission vehicles, which may be verified by underhood Emission Control label. California emissions may be available in other states.

Before testing separate components or systems, perform procedures in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Since many computer-controlled and monitored components set a diagnostic trouble code if they malfunction, also perform procedures in appropriate SELF-DIAGNOSTICS article.

NOTE: Testing individual components does not isolate short or open circuits. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate shorted or open wiring harness.

NOTE: When performing test procedures, technican may be instructed to use scan tool during testing procedure. This scan tool may also be referred to as Toyota hand-held tester. If using OBD-II scan tool, this scan tool may not have all of the capabilities as the Toyota hand-held tester.