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Read ECM%20DTC%20guide%20manual.pdf

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Service Manual Trucks

Group 28

Engine Control Module (ECM), Diagnostic Trouble Code (DTC), Guide 2010 Emissions CHU, CXU, GU, TD

PV776-88961816

Foreword

The descriptions and service procedures contained in this manual are based on designs and methods studies carried out up to March 2010. The products are under continuous development. Vehicles and components produced after the above date may therefore have different specifications and repair methods. When this is believed to have a significant bearing on this manual, supplementary service bulletins will be issued to cover the changes. The new edition of this manual will update the changes. In service procedures where the title incorporates an operation number, this is a reference to a Labor Code (Standard Time). Service procedures which do not include an operation number in the title are for general information and no reference is made to a Labor Code (Standard Time). Each section of this manual contains specific safety information and warnings which must be reviewed before performing any procedure. If a printed copy of a procedure is made, be sure to also make a printed copy of the safety information and warnings that relate to that procedure. The following levels of observations, cautions and warnings are used in this Service Documentation: Note: Indicates a procedure, practice, or condition that must be followed in order to have the vehicle or component function in the manner intended. Caution: Indicates an unsafe practice where damage to the product could occur. Warning: Indicates an unsafe practice where personal injury or severe damage to the product could occur. Danger: Indicates an unsafe practice where serious personal injury or death could occur.

Mack Trucks, Inc.

Greensboro, NC USA

Order number: PV776-88961816 Repl: ©2010 Mack Trucks, Inc., Greensboro, NC USA All rights reserved. No part of this publication may be reproduced, stored in retrieval system, or transmitted in any forms by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of Mack Trucks, Inc.

USA40713

Contents

Design and Function.................................................................................................................... 3 Engine Control Module (ECM)...................................................................................................... 3 On Board Diagnostic (OBD) Monitors............................................................................................ 4 Troubleshooting .......................................................................................................................... 22 Engine Control Module (ECM) Diagnostic Trouble Codes (DTCs) ..................................................... 22

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Group 28

Engine Control Module (ECM)

Design and Function

Engine Control Module (ECM)

The manufacturer scan tool is the preferred tool for performing diagnostic work. Contact your local dealer for more information or visit "". Note: The use of a scan tool is necessary to perform diagnostic work as well as clearing of any diagnostic trouble codes (DTCs). DTC(s) can no longer be cleared using the vehicles instrument cluster digital display and stalk switch control.

System Overview

Six electronic control units (ECUs) are used; the engine control module (ECM), instrument control module (ICM), Vehicle Electronic Control Unit (VECU), transmission control module (TCM), the gear selector control module (GSCM) and the aftertreatment control module (ACM). Together, these modules operate and communicate through the SAE J1939 (CAN 1) data link to control a variety of engine and vehicle cab functions. The ECM controls such things as fuel timing and delivery, fan operation, engine protection functions, engine brake operation, the exhaust gas recirculation (EGR) valve and the turbocharger nozzle. The VECU controls cruise control functions, accessory relay controls and idle shutdown functions. The ICM primarily displays operational parameters and communicates these to the other ECUs. All have the capability to communicate over the SAE J1587 data link primarily for programming, diagnostics and data reporting. In addition to their control functions, the modules have on board diagnostic (OBD) capabilities. The OBD is designed to detect faults or abnormal conditions that are not within normal operating parameters. When the system detects a fault or abnormal condition, the fault will be logged in one or both of the modules' memory, the vehicle operator will be advised that a fault has occurred by illumination a malfunction indicator lamp (MIL) and a message in the driver information display, if equipped. The module may initiate the engine shutdown procedure if the system determines that the fault could damage the engine. In some situations when a fault is detected, the system will enter a "derate" mode. The derate mode allows continued vehicle operation but the system may substitute a sensor or signal value that may result in reduced performance. In some instances, the system will continue to function but engine power may be limited to protect the engine and vehicle. Diagnostic trouble codes (DTCs) logged in the system memory can later be read, to aid in diagnosing the problem using a diagnostic computer or through the instrument cluster display, if equipped. When diagnosing an intermittent DTC or condition, it may be necessary to use a scan tool connected to the Serial Communication Port. The use of a scan tool is necessary to perform diagnostic work as well as clearing of any diagnostic trouble codes (DTCs). DTC(s) can no longer be cleared using the vehicles instrument cluster digital display and stalk switch control. Additional data and diagnostic tests are available when a scan tool is connected to the Serial Communication Port. For diagnostic software, contact your local dealer. The ECM is a microprocessor based controller programmed to perform fuel injection quantity and timing control, diagnostic fault logging, and to broadcast data to other ECUs. The fuel quantity and injection timing to each cylinder is precisely controlled to obtain optimal fuel economy and reduced exhaust emissions in all driving situations. The ECM controls the operation of the injectors, engine brake solenoid, EGR valve, turbocharger nozzle position, and cooling fan clutch based on inputs from many sensors and information received over the data links from other ECUs. The VECU and ECM are dependent on each other to perform their specific control functions. In addition to switch and sensor data, the broadcast of data between modules also includes various calculations and conclusions that each module has developed, based on the input information it has received.

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On Board Diagnostic (OBD) Monitors

On Board Diagnostic (OBD) Monitors

System Electronic Control Unit (ECU) Overview

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