Isuzu KB P190. Service manual — part 266

6E-30 Engine Control System (4JH1)

Diagnostic Information And Prosedures

Engine Control System Check Sheet

ENGINE CONTROL SYSTEM CHECK SHEET

Inspectors Name

Customer’s Name

Model & Model Year

Driver’s Name

Chassis No.

Date Vehicle Brought In

Engine No.

License No.

Odometer Reading

Km/miles

□

Engine Does
Not Run

□

Engine does not crank

□

No initial combustion

□

No complete combustion

□

Hard Start

□

Engine cranks slowly

□

Other (

)

□

Abnormal idling speed

□

High idling speed ( RPM)

□

Low idling speed ( RPM)

□

Rough

idling

□

Incorrect Idle

□

Other (

)

□

Hesitation, sag, stumble

□

Surge, chuggles

□

Cut out, misses

□

Lack of power, sluggishness, sponginess

□

Poor
Driveability

□

Other (

)

□

Soon after starting

□

After accelerator pedal depressed

Engine Stall

□

During A/C operation

□

After accelerator pedal released

□

Shifting from N to D

□

□

Other (

)

□

Black smoke

□

White smoke

□

Poor fuel economy

□

Fuel knock, combustion noise

P

roblem

S

ym

pt

om

s

□

Others

□

Other (

)

Dates problem occurred

□

Constant

□

Intermittently ( times per day/month)

□

Once only

Problem frequency

□

Other (

)

□

Fine

□

Cloudy

□

Rainy

□

Snow

Weather

□

Various/Other (

)

□

Hot (approx. ) □ Warm

□

Cool

□

Cold (approx. )

Outside
Temperature

□

Any

temperature

□

Highway

□

Suburbs

□

City area

□

Uphill

Place

□

Downhill

□

Rough road

□

Other (

)

□

Over (approx.

tons)

□

No load

Load Condition

□

Other (approx.

tons)

□

Cold

□

Warming up

□

After warming up

□

Any temperature

Engine
Temperature

□

Other (

)

□

Starting

□

Just after starting (

Min.)

□

Idling

□

Racing

□

Driving

□

Constant speed

□

Acceleration

□

Deceleration

□

A/C switch On/Off

Engine Operation

□

Other (

)

Fuel Amount

□

Full

□

Above 1/2

□

Below 1/2

□

Near empty

Condit

ion When P

roblem

Oc

cu

rs

Fuel

Bland

Condition of MIL

□

Remains On

□

Intermittently turns On

□

Does not turn On

Present Code

□

Nothing

□

P Code & Symptom Code
No. (

)

Diagnostic Trouble
Code (DTC) or Flash
Code

History Code

□

Nothing

□

P Code & Symptom Code
No. (

)

Other Additional
Condition

Engine Control System (4JH1) 6E-31

Diagnostic Starting Point - Engine Controls

Begin the system diagnosis with Diagnostic System
Check - Engine Controls. The Diagnostic System Check
- Engine Controls will provide the following information:

• The identification of the control modules which

command the system.

• The ability of the control modules to communicate

through the serial data circuit.

• The identification of any stored diagnostic trouble

codes (DTCs) and the their statuses.

The use of the Diagnostic System Check - Engine
Controls will identify the correct procedure for
diagnosing the system and where the procedure is
located.
Important:
Engine Control System Check Sheet must be used to
verify the complaint vehicle, you need to know the
correct (normal) operating behavior of the system and
verify that the customer complaint is a valid failure of
the system.

Reading Flash Diagnostic Trouble Codes
The provision for communicating with the ECM is the
Data Link Connector (DLC). The DTCs stored in the
ECM memory can be read either through a hand-held
diagnostic scanner such as scan tool plugged into the
DLC or by counting the number of flashes of the MIL
when the diagnostic test terminal of the DLC is
grounded. The DLC terminal “6” (diagnostic request
switch) is pulled “Low” (grounded) by jumped to DLC
terminal “4”, which is a ground wire.
Once terminals “4” and “6” have been connected, the
ignition switch must be moved to the “ON” position, with
the engine not running. The MIL will initially flash 12.
Then, the MIL will flash the first stored DTC three times,
second stored DTC three times and so on. All the
stored DTCs are flashed, then return 12 and continue to
flash the DTC. If no DTC exists, the MIL flashes 12
continuously. The flash DTC display will continue as
long as the DLC is shorted.

RTW66ESF000501

6E-32 Engine Control System (4JH1)

Breaker Box

Breaker Box Connection Type A

RTW66ESH003601

Legend

1. Engine Control Module (ECM)
2. Harness Adapter
3. ECM - Harness Connector
4. Breaker Box
5. ECM is disconnected

Breaker Box Connection Type B

RTW66ESH003701

Legend

1. Engine Control Module (ECM)
2. Harness Adapter
3. ECM - Harness Connector
4. Breaker Box
5. ECM is connected

Although probe to the engine control module (ECM)
harness connector is possible by Test Adapter,
Breaker Box Connection Type A is suitable usage to
prevent misprobe and damage of female terminals
when test open circuit or short to ground between the
ECM and electrical components, since the terminals
where the harness connector of the ECM is thin have
gathered.

The ECM and other connectors have water proof
terminal that is not allowed to back probe. Breaker
Box Connection Type B is suitable usage to test short
to voltage circuit or signal check between the ECM
and electrical components.

Engine Control System (4JH1) 6E-33

Diagnostic System Check - Engine

Controls

Description
The Diagnostic System Check-Engine Controls is an
organized approach to identifying a condition that is
created by a malfunction in the electronic engine control
system. The Diagnostic System Check must be the
starting point for any driveability concern. The
Diagnostic System Check directs the service technician
to the next logical step in order to diagnose the concern.
Understanding and correctly using the diagnostic table
reduces diagnostic time, and prevents the replacement
of good parts.
Test Description
The numbers below refer to the step numbers on the
diagnostic table.
2. Lack of communication may be because of a partial
or a total malfunction of the Keyword 2000 serial data
circuit. The specified procedure determines the
particular condition.

11. If there are other modules with DTCs set, refer to
the DTC list. The DTC list directs you to the appropriate
diagnostic procedure. If the control module stores
multiple DTCs, diagnose the DTCs in the following
order.
• Component level DTCs, such as sensor DTCs,

solenoid DTCs, actuator DTCs, and relay DTCs.
Diagnose the multiple DTCs within this category in
numerical order. Begin with the lowest numbered
DTC, unless the diagnostic table directs you
otherwise.

Important:

• DO NOT perform this diagnostic if there is not a

driveability concern, unless another procedure
directs you to this diagnostic.

• Before you proceed with diagnosis, search for

applicable service bulletins.

• Unless a diagnostic procedure instructs you, DO

NOT clear the DTCs.

• If there is a condition with the starting system, refer

to the starting system section in the engine
mechanical.

• Ensure the battery has a full charge.
• Ensure the battery cables (+) (-) are clean and

tight.

• Ensure the ECM grounds are clean, tight, and in

the correct location.

• Ensure the ECM harness connectors are clean and

correctly connected.

• Ensure the ECM terminals are clean and correctly

mating.

• Ensure the fuel injection pump control unit (PCU)

ground is clean, tight, and in the correct location.

• Ensure the PCU harness connectors are clean and

correctly connected.

• Ensure the PCU terminals are clean and correctly

mating.

• Ensure the vehicle maintenance has been done

enough.

Step Action

Value(s)

Yes

No

1

Install the scan tool.
Does the scan tool turn ON?



Go to Step 2

Go to scan tool

Does Not Power Up