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Engine Controls - System & Component Testing: Introduction

CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle.
NOTE: For system and component testing information not covered in this article, see corresponding system or component fault code definition under TROUBLE CODE IDENTIFICATION CHART in appropriate SELF-DIAGNOSTICS article. Perform appropriate fault code test.
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.

Before testing separate components or systems, follow proper workflow. If a no start condition exists, proceed to appropriate BASIC DIAGNOSTIC PROCEDURES article. If a driveability condition exists, proceed to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).