Engine Controls - System/Component Tests: Introduction

Before testing separate components or systems, perform procedures in BASIC TESTING article. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in SELF-DIAGNOSTICS - 4.0L article.

NOTE: Testing individual components does not isolate shorted 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 wiring harness shorted or open circuits.