Isuzu 727 N SERIES 4HK1 Engine Control System Workshop Manual (EN)

N O T I C E Before using this Workshop Manual to assist you in performing vehicle service and maintenance operations, it is recommended that you carefully read and thoroughly understand the information contained in Section - 0A under the headings “GENERAL REPAIR INSTRUCTIONS” and “HOW TO USE THIS MANUAL”. All material contained in this Manual is based on the latest product information available at the time of publication. All rights are reserved to make changes at any time without prior notice.

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ENGINE

Engine Control System 1A-1 ENGINE Engine Control System CONTENTS Engine Control System . . . . . . . . . . . . . . . . . . . . 1A-2 Precautions on Service . . . . . . . . . . . . . . . . . . . 1A-2 Function and Operation. . . . . . . . . . . . . . . . . . . 1A-4 Component Layout . . . . . . . . . . . . . . . . . . . . . 1A-20 Circuit diagram . . . . . . . . . . . . . . . . . . . . . . . . 1A-25 Strategy-Based Diagnostics . . . . . . . . . . . . . . 1A-31 Functional Check List . . . . . . . . . . . . . . . . . . . 1A-37 Hearing Diagnostic . . . . . . . . . . . . . . . . . . . . . 1A-37 On-Board Diagnostic (OBD) System Check . . 1A-39 Inactive CHECK ENGINE Lamp (MIL) . . . . . .

1A-41 CHECK ENGINE Lamp (MIL) Remains Active 1A-44 Engine Cranks But Will Not Run . . . . . . . . . . . 1A-46 Diagnosis with Tech 2 Scan Tool. . . . . . . . . . . 1A-48 Diagnostic Chart . . . . . . . . . . . . . . . . . . . . . . . 1A-67 DTC11 - No Signal CKP Sensor . . . . . . . . . . . 1A-73 DTC13 - TCV Fault . . . . . . . . . . . . . . . . . . . . . 1A-75 DTC14 - Pump ROM Fault . . . . . . . . . . . . . . . 1A-78 DTC15 - Pump Cam Sensor (NE Sensor) Short Break Fault . . . . . . . . . . . . . . . . . . . . . . 1A-80 DTC16 - No Signal from Pump Cam Sensor (NE Sensor) . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-82 DTC21 - ECT Sensor Fault. . . . . . . . . . . . . . .

1A-84 DCT23 - IAT Sensor Fault. . . . . . . . . . . . . . . . 1A-88 DTC24 - AP Sensor Output Fault . . . . . . . . . . 1A-91 DTC25 - VS Sensor Circuit Fault . . . . . . . . . . 1A-95 DTC31 - Idle Up Volume Fault . . . . . . . . . . . . 1A-98 DTC32 - MAP Sensor Fault . . . . . . . . . . . . . 1A-101 DTC34 - Exhaust Brake Open Wiring Fault . 1A-104 DTC35 - Neutral Switch Signal Fault . . . . . . 1A-106 DTC36 - Clutch Switch Signal Fault (M/T Vehicle only) . . . . . . . . . . . . . . . . . . . . . 1A-108 DTC41 - FT Sensor Circuit High Voltage . . . 1A-110 DTC51 - Atmospheric Pressure Sensor Fault 1A-113 DTC52 - ECM Internal Fault . . . . . . . . . . . . .

1A-114 DTC53 - Engine Driver Unit Fault . . . . . . . . . 1A-116 DTC55 - Pump Unmatched (Difference from ECM Specifications). . . . . . 1A-118 DTC65 - Idle Position Switch Fault . . . . . . . . 1A-120 Symptom Diagnosis Chart . . . . . . . . . . . . . . 1A-122 Hard Starting. . . . . . . . . . . . . . . . . . . . . . . . . 1A-123 Vehicle Speed Variation . . . . . . . . . . . . . . . . 1A-127 Lack Power or Faulty Response . . . . . . . . . . 1A-130 Unstable Idling . . . . . . . . . . . . . . . . . . . . . . . 1A-134 Engine Not Stall . . . . . . . . . . . . . . . . . . . . . . 1A-137 Starter Motor does Not Run . . . . . . . . . . . . . 1A-139 Quick On Start (QOS) System does Not Operate . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . 1A-142 Excessive Black Smoke in Exhaust Gas. . . . 1A-144 Excessive White Smoke in Exhaust Gas . . . 1A-147 Noisy Engine. . . . . . . . . . . . . . . . . . . . . . . . . 1A-149 Nasty Smell. . . . . . . . . . . . . . . . . . . . . . . . . . 1A-152 Poor Fuel Economy. . . . . . . . . . . . . . . . . . . . 1A-155 Excessive Engine Oil Consumption . . . . . . . 1A-159 Large Engine Vibration . . . . . . . . . . . . . . . . . 1A-161 Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . 1A-164 Wiring Harness Repair: Shielded Cable. . . . . . 1A-165 Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-165 Installation Procedure . . . .

. . . . . . . . . . . . . . 1A-165 Twisted Leads . . . . . . . . . . . . . . . . . . . . . . . . . 1A-166 Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-166 Installation Procedure . . . . . . . . . . . . . . . . . . 1A-166 Weather-Pack Connector. . . . . . . . . . . . . . . . . 1A-168 Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-168 Installation Procedure . . . . . . . . . . . . . . . . . . 1A-168 Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . 1A-169 Com-Pack III. . . . . . . . . . . . . . . . . . . . . . . . . . . 1A-170 General Information . . . . . . . . . . . . . . . . . . . 1A-170 Metri-Pack . . . . . . . . . . . . . . . . . . . . . . . . . . .

. 1A-171 Removal Procedure . . . . . . . . . . . . . . . . . . . 1A-171 Installation Procedure . . . . . . . . . . . . . . . . . . 1A-171 Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . 1A-171

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Precautions on Service

1A-2 Engine Control System Engine Control System Precautions on Service Circuit Test Tools Damage by Electrostatic Discharge Electronic components used in the electronic control system are designed to work at very low voltages and, for this reason, they are susceptible to damage by electrostatic discharge and some types of electronic components may be damaged even by the static electricity of less than 100 V that is usually not sensed by persons. Persons’ sensitivity level is 4,000 V. Persons are electrostatically charged in various ways and the most typical electrification sources are friction and induction. Shown below are examples.

Electrification by friction occurs when a person slides on the seat in the vehicle. Electrification by induction occurs when a person with insulating shoes is standing near a highly electrifiable substance and touches a ground momentarily. Electric charges with the same polarity flow out and resultantly the person is charged at high opposite polarity. Since static electric charges cause damages, it is important when you handle or test electronic components. Unless otherwise specified in diagnostic procedures, do not use Test Light to diagnose the powertrain electrical system. When diagnostic procedures need probe connector, use Connector Test Adapter Kit 5- 8840-0385-0.

On-Market Electrical Equipment and Vacuum Devices On-market electrical equipment and vacuum devices refer to those components that will be installed to vehicles after shipment from manufacturing plants. Be careful that installation of these components is not considered during the process of vehicle design. CAUTION: Do not install on-market vacuum devices to vehicles. CAUTION: Connect on-market electrical equipment, as well as its power supplies and grounds, to the circuits isolated from the electronic control system. CAUTION: To prevent damages by electrostatic discharge, follow the guidelines shown below.

Do not touch ECM connector pins as well as electronic components soldered to the ECM circuit board. Do not unpack each replacement component until preparations are completed for the component. Before taking out a component from the package, connect the package to the normal grounding line of the vehicle. When you intend to slide on the seat, change the posture from standing to sitting, or walk by a certain distance to handle a component, touch an appropriate grounding material. The on-market electrical equipment, even when installed to vehicles in normal manner, may bring functional troubles to the electronic control system.

Affected devices include those not connected to the vehicle electrical equipment system, for example, mobile phones or radios. Therefore, when you intend to diagnose the powertrain, check such the on-market electrical equipment has not been installed to the vehicle and, if installed, remove it. If faults still occur even after removal of on-market electrical equipment, diagnose the vehicle according to normal procedures.

List of Abbreviations Abbreviation Original form Meaning in this manual A/C Air Conditioner Air conditioning units (cooler, heater, etc.) AP Accelerate Position Depressing stroke of accelerator pedal CKP Crankshaft Position Rotating reference signal of crankshaft CMP Camshaft Position Rotating reference signal of pump camshaft DLC Data Link Connector DLC connector (Tech 2 communication connector) DTC Diagnosis Trouble Code DTC code DVM Digital Volt Meter Special service tool (part No. 5-8840-0366-0) ECT Engine Coolant Temperature Coolant temperature ECM Engine Control Modulle Engine control computer EDU Engine Driver Unit Fuel pump spill valve drive unit

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Precautions on Service

Engine Control System 1A-3 Wire Color All wiring harnesses are identified using colored jacket. The wiring harness used for the main circuit in an electrical system is identified with single color while the wiring harness used for the sub-circuit is identified with color stripe. The following rule is used in each wiring diagram to indicate size and color of a wiring harness. Legend 1. Red (stripe color) 2. Green (base color) 3.

Harness size (0.5 mm 2 ) Abbreviation Original form Meaning in this manual EGR Exhaust Gas Recirculation Exhaust gas recirculation ISM Intake Step Motor Intake throttle valve drive motor ITP Intake Throttle Position Intake throttle valve opening MIL Malfunction Indicator Lamp CHECK ENGINE Lamp SPV Spill Control Valve Valve for high pressure circuit in the fuel pump SW Switch TCV Timing Control Valve Injection timing control valve in the fuel pump Key SW Key switch Starter switch eg. : 0.5 GRN / RED 1 2 3 LNW21ASH000101-X Symbol Color Symbol Color B Black BR Brown W White LG Light green R Red GR Gray G Green P Pink Y Yellow LB Light blue L Blue V Violet O Orange

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