Engine Controls - System & Component Testing: Introduction

Before testing separate components or systems, perform procedures in BASIC DIAGNOSTIC PROCEDURES article. If system or component testing procedure is not cover in this article, and since many computer-controlled monitored components, or related control system circuits can set a trouble code if they malfunction, also perform procedures in appropriate SELF-DIAGNOSTICS article.

CAUTION: When battery is disconnected, vehicle computer and memory system may lose memory data. Driveability problems may exist until computer system have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

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

NOTE: For assistance on component harness connectors wire color(s) and pin connector number(s), see appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS.