Engine Controls - Basic Diagnostic Procedures: Introduction

NOTE: For basic diagnostic procedures on I30, refer to Maxima in Nissan BASIC DIAGNOSTIC PROCEDURES article. For basic diagnostic procedures on QX4, refer to Pathfinder in Nissan BASIC DIAGNOSTIC PROCEDURES article.

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition. The first step in diagnosing any driveability problem is verifying customer complaint with a test drive under conditions problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article. Manufacturer provides a specific order for diagnosing engine performance-related problems. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS.

NOTE: Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance unless otherwise instructed in test procedure.