Engine Controls - System & Component Testing: Introduction

Before testing separate components or systems, perform appropriate procedures in BASIC DIAGNOSTIC PROCEDURES article. Since many computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) if they malfunction, also perform procedures in SELF-DIAGNOSTICS - B2300, B2500, B3000, B4000 & TRIBUTE 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. For identification of circuits and terminals referenced in test procedures, see WIRING DIAGRAMS article.