Isuzu N-Series. Manual - part 424

6E-32 EMISSION AND ELECTRICAL DIAGNOSIS

Notice:
The meaning of symbol marks are:

Connec-
tor 22 pin

1

EGR Cut Magnetic Valve Power Supply

×

❍

❍

2

Glow Relay

❍

❍

❍

3

Glow Indicator Lamp

❍

❍

❍

4

Rack Idle Position Out Put

5

Not be used

—

—

—

6

Not be used

—

—

—

7

Engine Coolant Temperature Sensor GND

❍

❍

❍

8

Engine Coolant Temperature Sensor SIG

❍

❍

❍

9

Engine Revolation Sensor GND

❍

❍

❍

10

Engine Revolation Sensor SIG

❍

❍

❍

11

VSS Magnetic Valve Power Supply

×

❍

❍

12

QWS Relay

❍

❍

❍

13

Aneroid Compensator Magnetic Valve

❍

❍

❍

14

Not be used

—

—

—

15

Not be used

—

—

—

16

Not be used

—

—

—

17

Not be used

—

—

—

18

Starter Switch

❍

❍

❍

19

Exhaust Brake Status Switch

❍

❍

❍

20

Not be used

—

—

—

21

Not be used

—

—

—

22

Not be used

—

—

—

Equipped 

without 

EGR and 

VSS

Equipped with EGR and 

VSS

Connector

Connector 

number

Connector name

4HE1-XS

4HE1-XN

4HE1-XS

❍: Connect

BLANK: Not

×: Not Connect

EMISSION AND ELECTRICAL DIAGNOSIS 6E-33

Location of the Engine Control Module (ECM) Connector

Location of Data Link Connector (DLC)

Legend

A. 30 pins connector (green)

1. Engine control module (ECM)

B. 22 pins connector (green)

Legend

A. Right-hand drive

C. Terminal assignment of data link connector (DLC)

B. Left-hand drive

N6A1143E

N6A1665E

6E-34 EMISSION AND ELECTRICAL DIAGNOSIS

NO

TERMINAL NAME

6

DIAG CONTROL

7

CHECKER SIG

4, 5

CHECKER GND

N6A1666E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-35

BRIEF EXPLANATION OF EMISSION AND ELECTRICAL CONTROL SYSTEM

MITICS (Mechanically Integrated Timing
and Injection Control System)

The Mechanically Integrated Timing and Injection rate
Control System (MITICS) utilizes mechanical control, in
comparison with TICS systems, which utilize electronic
control.
MITICS is equipped with the RLD-M type governor,
which contains a pre-stroke control mechanism. 
With this, pre-stroke position (i.e., beginning of static in-
jection) can be varied to control injection timing and in-
jection rate (i.e., the fuel injection quantity injected from
the nozzle per cam angle degree).
This enables high injection rates1 in the low and medi-
um speed ranges through a short Injection interval, thus
contributing to higher engine torque and cleaner ex-
haust.
MITICS was developed in response to the demands of
medium sized diesel engines for low cost, low fuel con-
sumption, high output and cleaner emissions.

High injection rates using a short injection interval.

• The speed at which the injection pump plunger ris-

es slows as engine speed decreases and the pres-
sure inside the injection pipe decreases.
Because of this, the nozzle spray deteriorates and
makes it impossible to obtain the proper fuel - air
mixture.
To obtain the proper mixture at low and medium
speeds, it is necessary to increase the pressure in-
side the injection pipes using a short injection inter-
val.

• The left hand figure shows plunger speed and cam

lift in relation to cam angle. It can be seen from the
graph that plunger speed increases together with
cam lift.
MITICS varies the beginning of injection position at
low and medium speeds so that injection occurs
when the plunger speed increases during the latter
half of cam lift (shown by the bold line).
At high speeds, injection is performed when the
plunger speed decreases during the first half of
cam lift to prevent an excessive increase in injec-
tion pipe pressure.
This enables high pressures at low and medium
speeds with a fast plunger speed. 
Thus, a fine fuel oil spray is injected into the cylin-
der from the nozzles within a short time to provide
the proper mixture for combustion, helping to in-
crease torque and keep exhaust emissions clean.

Legend

1. Injection pipe pressure
2. Engine speed
3. PE-AD type injection pump

N6A1145E

Legend

1. Plunger speed (m/sec)
2. Cam angle (degrees)
3. Cam lift (mm)
4. Plunger speed
5. Cam lift

N6A1146E