Isuzu N-Series. Service manual - part 645

6E-2    Engine Control System (4HK1) 

Cut Out, Misses.............................................  6E-317
Surges / Chuggles.........................................  6E-318
Lack of Power, Sluggishness, Sponginess ...  6E-320
Hesitation, Sag, Stumble...............................  6E-321
Fuel Knock / Combustion Noise....................  6E-323
Poor Fuel Economy.......................................  6E-325
Excessive Smoke (Black Smoke) .................  6E-326
Excessive Smoke (White Smoke) .................  6E-327

Repair Instructions ...........................................  6E-330

Engine Control Module (ECM) Replacement / 
Fuel Injector ID Code Data Programming .....  6E-330
Accelerator Pedal Position (APP) Sensor 
Replacement .................................................  6E-332
Barometric Pressure (BARO) Sensor 
Replacement .................................................  6E-334
Boost Pressure Sensor Replacement ...........  6E-334
Camshaft Position (CMP) Sensor Replacement

......................................................................  6E-335

Crankshaft Position (CKP) Sensor Replacement

......................................................................  6E-335

EGR Valve Replacement ..............................  6E-336
Engine Coolant Temperature (ECT) Sensor 
Replacement .................................................  6E-337
Fuel Injector Replacement / Fuel Injector ID Code
Data Programming ........................................  6E-338
Fuel Rail Pressure (FRP) Sensor Replacement

......................................................................  6E-344

Fuel Pressure Limiter Replacement..............  6E-344
Fuel Rail Replacement..................................  6E-346
Fuel Supply Pump Replacement...................  6E-349
Fuel System Air Bleeding..............................  6E-353
Idle Up Sensor Replacement ........................  6E-354
Intake Air Temperature (IAT) Sensor Replacement

......................................................................  6E-354

Vehicle Speed Sensor (VSS) Replacement..  6E-354

Description and Operation ...............................  6E-356

Engine Control Module (ECM) Description ...  6E-356
Engine Control Component Description........  6E-358
Fuel System Description ...............................  6E-362
Fuel System Component Description............  6E-363
Fuel Injection Quantity Control Description...  6E-367
Fuel Injection Timing Control Description .....  6E-368
Exhaust Gas Recirculation (EGR) System 
Description ....................................................  6E-368
Turbocharger Description..............................  6E-368

Special Tools and Equipment ..........................  6E-370

Special Tools and Equipment .......................  6E-370

 Engine Control System (4HK1)    6E-3

Specifications

Temperature vs Resistance

Engine Coolant Temperature vs. Resistance

Intake Air Temperature vs. Resistance

Fuel Temperature vs. Resistance

Altitude vs Barometric Pressure

°C

°F

Ω

Temperature vs. Resistance Value (Approximately)

110

230

160

100

212

200

90

194

260

80

176

350

70

158

470

60

140

640

50

122

880

40

104

1250

30

86

1800

20

68

2650

10

50

4000

0

32

6180

-10

14

9810

-20

-4

16000

-30

-22

27000

°C

°F

Ω

Temperature vs. Resistance Value (Approximately)

90

194

240

80

176

320

70

158

450

60

140

660

50

122

960

40

104

1440

30

86

2300

20

68

3430

10

50

5410

0

32

9770

-10

14

16410

20

-4

28560

°C

°F

Ω

110

230

140

100

212

180

90

194

240

80

176

310

70

158

420

60

140

580

50

122

810

40

104

1150

30

86

1660

20

68

2450

10

50

3700

0

32

5740

-10

14

9160

-20

-4

15000

-30

-22

25400

Altitude Measured 

in Meters (m)

Altitude Measured 

in Feet (ft)

Barometric 

Pressure 

Measured in 

Kilopascals (kPa)

Determine your altitude by contacting a local weather
station or by using another reference source.

4267

14000

56-64

3962

13000

58-66

3658

12000

61-69

3353

11000

64-72

3048

10000

66-74

2743

9000

69-77

2438

8000

71-79

2134

7000

74-82

1829

6000

77-85

1524

5000

80-88

1219

4000

83-91

914

3000

87-98

610

2000

90-98

305

1000

94-102

0

0 Sea Level

96-104

-305

-1000

101-105

°C

°F

Ω

6E-4    Engine Control System (4HK1) 

Schematic and Routine Diagrams

Engine Controls Schematics

Power Distribution

SBF-2

KEY

40A

SBF-1

MAIN

100A or 120A

2L

30

BLK/

RED

8 BLK

0.3

GRN/

ORN

3

WHT/

BLK

F-1

HEATER,

AIR CON

15A

Heater &

A/C Relay

1

2

X-12

5

4

X-12

F-2

FUEL

HEATER

10A

F-7

TAIL

LIGHT

10A

Heater

Relay

1

2

X-8

5

4

X-8

Tail

Relay

1

2

X-4

5

4

X-4

Charge

Relay

3

BLK/

RED

3

BLU

5

WHT

5

WHT/

BLK

8

WHT/

BLK

3

WHT/

BLK

3

WHT/

BLK

0.5

WHT/

RED

0.5 WHT/RED

3

WHT

F-22

STARTER

10A

F-9

ENG.

(IG)

10A

F-16

METER

10A

3

BLK/

YEL

W/S-H

W/S-E

USW

JOINT 3

3

BLK/

YEL

3

BLK

0.5

BLK

2

BLK

0.5 BLK

B-67

4

H-6

2

H-7

1

SBF-3

GLOW

60A

3

BLK/

BLU

0.5

BLK

3

WHT/

RED

1.25

RED

Glow

Plug

Relay

3

4

X-20

2

5

X-20

SBF-8

STARTER

60A

Fuse &

Relay Box

(Behind

the Cab)

Fuse &

Relay Box

(Behind

the Cab)

Fuse &

Relay Box

(Glove Box)

Relay Box

(Instrument

 Panel)

Relay Box

(Instrument

 Panel)

Fuse &

Relay Box

(Glove Box)

Fuse &

Relay Box

(Glove Box)

SBF-5

ECM

40A

ECM

Main

Relay

Starter

Relay

ECM

ECM

Combination

Switch

Glow

Plug

ECM

0.5

BLU/

BLK

2

RED

0.5

BLK/

RED

3

BLK/

YEL

3

WHT/

BLK

2

BLK

J-9

Frame

2

ST

ON

ACC

OFF

B-67

3

B-67

Ignition

Switch

Fuse &

Relay Box

(Behind the Cab)

P-5

B-7

H/L

 Bracket

6

J/C-D

1

Battery

P-1

P-2

P-3

P-4

N6A6628E

0.5

YEL/

BLK

3

5

X-18

2

4

X-18

F-28

ECM

10A

 Engine Control System (4HK1)    6E-5

Starting System

ECM

TCM

30 BLK/RED

8 BLK

8 BLK

8 BLK

3 BLK/YEL

P-1

P-2

P-3

P-4

Battery

P-5

3

BLK/

WHT

3

WHT/

BLK

0.5

RED/WHT

0.5

RED/WHT

0.5

RED

0.5

WHT/

BLU

0.3

BLK/WHT

3

WHT/BLU 

3

WHT/BLU 

2L

SBF-8

ST

AR

TER

60A

SBF-2

KEY

40A

F-22

ST

AR

TER

10A

14

H-8

0.5

RED/

WHT

0.5

WHT/

BLU

0.5

WHT/

BLU

J-9

Frame

1

H-7

4

B-67

USW

JOINT

 3

2

BLK

0.5

BLK

14

J-191

B-425

46

Start cut

relay

control

Start switch

signal

38

H-5

16

Starter

cut

relay

control

Fuse &

Relay Box

(Glove Box)

F-28

ECM

10A

Fuse &

Relay Box

(Behind the Cab)

2

B-67

2

3

J/C-2

0.85

L

T

 GRN

0.5

L

T

 GRN

ECM

Main Relay

5

2

X-21

4

3

X-21

5

1

X-26

3

4

X-26

ST

ON

ACC

OFF

Ignition

Switch

N6A6629E

Starter

B

C

1

J-27

1

J-26

Fuse &

Relay Box

(Behind 

the Cab)

Starter

Relay

Fuse &

Relay Box

(Behind the Cab)

Fuse &

Relay Box

(Behind the Cab)

Starter Cut

Relay