Engine Controls - System & Component Testing: Introduction

NOTE: This article also applies to Infiniti I30 and QX4. For I30 coverage, refer to Maxima, unless otherwise indicated. For QX4 coverage, refer to Pathfinder, unless otherwise indicated.

NOTE: The terms ECM (Electronic Control Module) and PCM (Powertrain Control Module) are used interchangeably to refer to the engine control computer.

Before testing separate components or systems, perform procedures in BASIC DIAGNOSTIC PROCEDURES article. Since the introduction of OBD-II, most all computer-controlled and monitored components set a Diagnostic Trouble Code (DTC) if they malfunction. Information for these components is covered in DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

NOTE: Testing individual components does not isolate a short or open circuit. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.