Nissan Frontier. Manual

ENGINE CONTROL SYSTEM

EC-575

< WIRING DIAGRAM >

[VQ40DE FOR USA AND CANADA]

ABBIA2004GB

ENGINE CONTROL SYSTEM

EC-577

< WIRING DIAGRAM >

[VQ40DE FOR USA AND CANADA]

ABBIA1519GB

EC-578

< BASIC INSPECTION >

[VQ40DE FOR USA AND CANADA]

DIAGNOSIS AND REPAIR WORKFLOW

BASIC INSPECTION

DIAGNOSIS AND REPAIR WORKFLOW

Trouble Diagnosis Introduction

INFOID:0000000009481224

INTRODUCTION

The engine has an ECM to control major systems such as fuel con-

trol, ignition control, idle air control system, etc. The ECM accepts

input signals from sensors and instantly drives actuators. It is essen-

tial that both input and output signals are proper and stable. At the

same time, it is important that there are no malfunctions such as vac-

uum leaks, fouled spark plugs, or other malfunctions with the engine.

It is much more difficult to diagnose an incident that occurs intermit-

tently rather than continuously. Most intermittent incidents are

caused by poor electric connections or improper wiring. In this case,

careful checking of suspected circuits may help prevent the replace-

ment of good parts.

A visual check only may not find the cause of the incidents. A road

test with CONSULT (or GST) or a circuit tester connected should be

performed. Follow the Work Flow on “Work Flow”.

Before undertaking actual checks, take a few minutes to talk with a

customer who approaches with a driveability complaint. The cus-

tomer can supply good information about such incidents, especially

intermittent ones. Find out what symptoms are present and under

what conditions they occur. A Diagnostic Worksheet like the example

on “Worksheet Sample” should be used.

Start your diagnosis by looking for conventional malfunctions first.

This will help troubleshoot driveability malfunctions on an electroni-

cally controlled engine vehicle.

WORK FLOW

Overall Sequence

MEF036D

SEF233G

SEF234G

Nissan Frontier. Manual - part 501