Section 139 (Engine Controls - System & Component Testing - 4-Cylinder): Introduction

WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 2003 Toyota Tacoma, 2003 Toyota RAV4, 2003 Toyota Prius, 2003 Toyota Matrix, and 2003 Toyota MR2. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Before performing system and component testing procedures, check for any related Technical Service Bulletins (TSBs).

WARNING: On Prius, read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS .

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, follow proper workflow. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. If no Diagnostic Trouble Codes (DTC) are present and a no start condition exists, proceed to appropriate BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, proceed to TROUBLE SHOOTING & NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).

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