Engine Controls - System & Component Testing: Introduction

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 DVOM to isolate shorted or open wiring harness. For identification of circuits and terminals referenced in test procedures, see WIRING DIAGRAMS article.

Computer-controlled and monitored components should set a Diagnostic Trouble Code (DTC) if they malfunction. Perform QUICK TEST procedures in SELF-DIAGNOSTICS - VILLAGER article to check for DTCs prior to testing individual components. In many cases a circuit that is open, or shorted to ground or power can be at fault. Component replacement is only suggested after testing and passing circuits and control devices. A component test may direct you to a system test in SELF-DIAGNOSTICS - VILLAGER article to help avoid replacement of a good component. If the component can be tested individually, it will be included in this article.