Isuzu KB P190. Manual - part 267

6E-34  Engine Control System (4JH1) 

Step Action 

Value(s) 

Yes 

No 

2 

1.  Turn ON the ignition, with the engine OFF.  
2. Attempt to establish communication with the 

listed control modules. 

•  Engine control module (ECM) 
•  Transmission control module (TCM) (A/T 

only) 

•  Electronic hydraulic control unit (EHCU) 

Does the scan tool communicate with all the listed 
control modules? 

 

Go to Step 3 

Go to scan tool 

Does Not 

Communicate with 

Keyword 2000 

Device 

3 

Attempt to start the engine. 
Does the engine start and idle? 

 

Go to Step 4 

Go to Engine 

Cranks but Does 

Not Run 

4 

Select the DTC display function for the following 
control modules: 

• ECM 
•  TCM (A/T only) 
• EHCU 

Does the scan tool display any DTCs? 

 

Go to Step 5 

Go to Step 12 

5 

1.  Turn OFF the ignition for 30 seconds. 
2.  Start the engine. 
3.  Monitor the DTC Information with the scan tool. 
Did you complete the action? 

 

Go to Step 6 

 

6 

Does the scan tool display ECM DTC P0602? 

 

Go to Applicable 

DTC 

Go to Step 7 

7 

Does the scan tool display ECM DTC P0251 
(Symptom Code 9 or A), P0606 (Symptom Code A 
or B) or P1605 (Symptom Code C, D or E)? 

 

Go to Applicable 

DTC 

Go to Step 8 

8 

Does the scan tool display ECM DTC P0560 
(Symptom Code 1, 2 or A)? 

 

Go to Applicable 

DTC 

Go to Step 9 

9 

Does the scan tool display following ECM DTC 
P0561 (Symptom Code A or B) or P1625 (Symptom 
Code A or B)? 

 

Go to Applicable 

DTC 

Go to Step 10 

10 

Does the scan tool display following ECM DTC 
P1650 (Symptom Code A or B) or P1651 (Symptom 
Code A or B)? 

 

Go to Applicable 

DTC 

Go to Step 11 

11 

Is there any other code in any controller that has not 
been diagnosed? 

 

Go to Applicable 

DTC 

Go to Step 12 

12  Is the customer’s concern with the automatic 

transmission? 

 

Go to Diagnostic 

System Check 

Transmission 

Control 

Go to Step 13 

13 

Is the customer’s concern with the ABS system? 

 

Go to Diagnostic 

System Check 

Brake Control 

Go to Step 14 

Engine Control System (4JH1)  6E-35 

Step Action 

Value(s) 

Yes 

No 

14 

1.  Review the following symptoms. 
2. Refer to the applicable symptom diagnostic 

table: 

•  Hard Start  
•  Rough, Unstable, or Incorrect Idle and 

Stalling  

•  Cuts Out, Misses 
• Surge/Chuggles 
• Lack of Power, Sluggishness, or 

Sponginess 

•  Hesitation, Sag, Stumble 
•  Fuel Knock/Combustion Noise 
•  Poor Fuel Economy 
•  Excessive Smoke (Black Smoke) 
•  Excessive Smoke (White Smoke) 

Did you find and correct the condition? 

 

System OK 

Go to Intermittent 

Conditions 

 
 

6E-36  Engine Control System (4JH1) 

Scan Tool Data List 

The scan tool Data List contains all engine related
parameters that are available on the scan tool. Use the
scan tool Data List only after the following is
determined: 

•  The Diagnostic System Check - Engine Controls is

completed. 

•  No diagnostic trouble codes (DTCs) are present. 
•  On-board diagnostics are functioning properly. 

 

 
The scan tool values from a properly running engine 
may be used for comparison with the engine you are
diagnosing. The scan tool Data List represents values
that would be seen on a normal running engine. 
Important: 
A scan tool that displays faulty data should not be used.
The scan tool problem should be reported to the
manufacturer. Use of a faulty scan tool can result in
misdiagnosis and unnecessary parts replacement. Only 
the parameters listed below are referenced in this 
service manual for use in diagnosis. 
 

 

Scan Tool Parameter 

Units Displayed

Typical Data Value at 

Engine Idle 

Typical Data Value at 2000 

RPM 

Operating Conditions: Engine Idling or 2000 RPM / Engine Coolant Temperature is between 75-85

°C (167-185°F) / 

Accelerator Pedal is Constant / Park or Neutral / Accessories OFF / Vehicle Located at Sea Level 

Ignition Switch 

On/Off 

On 

On 

System Voltage 

V 

11.0 – 15.0 

11.0 – 15.0 

ECM Main Relay 

On/Off 

On 

On 

Engine Speed 

RPM 

650 - 750 

1950 – 2050 

Desired Idle Speed 

RPM 

700 

700 

Injection Pump Speed 

RPM 

325 - 375 

975 – 1025 

Accelerator Pedal Position 

% 

0.0 

5.0 – 7.0 

Idle Switch 

On/Off 

On 

Off 

Intake Air Temperature 

°C/°F 

20 – 40°C / 68 – 104°F 

20 – 40°C / 68 – 104°F 

Engine Coolant Temperature 

°C/°F 

75 - 85

°C / 167 - 185°F 

75 - 85

°C / 167 - 185°F 

Fuel Temperature 

°C/°F 

20 – 60°C / 68 – 140°F 

20 – 60°C / 68 – 140°F 

Barometric Pressure 

hPa 

Nearly 1010 hPa at sea level  Nearly 1010 hPa at sea level

Vacuum Pressure Sensor 

hPa 

Nearly 2020 hPa at sea level  Nearly 2020 hPa at sea level

Turbocharger Solenoid Command 

% 

100% at sea level 

100% at sea level 

EGR Solenoid Command 

% 

Nearly 90% 

Nearly 90% 

Mass Air Flow Sensor 

mg/strk 

More than 430 mg/strk at sea 

level (with EGR system)  

More than 700 mg/strk at sea 

level (without EGR system) 

More than 430 mg/strk at sea 

level (with EGR system)  

More than 700 mg/strk at sea 

level (without EGR system)

Desired Mass Air Flow 

mg/strk 

More than 430 mg/strk at sea 

level (with EGR system)  

1500 mg/strk (without EGR 

system) 

More than 430 mg/strk at sea 

level (with EGR system)  

1500 mg/strk (without EGR 

system) 

Actual Injection Quantity 

mg/strk 

6.0 – 9.0 

7.0 – 11.0 

Desired Injection Quantity 

mg/strk 

6.0 – 9.0 

7.0 – 11.0 

Actual Injection Timing 

°CA 

1.0 – 4.0 

3.0 – 4.5 

Desired Injection Timing 

°CA 

1.0 – 4.0 

3.0 – 4.5 

Neutral Switch 

On/Off 

On 

On 

Brake Pedal 1 Switch 

Applied/ Released

Released 

Released 

Brake Pedal 2 Switch 

Applied/ Released

Released 

Released 

Clutch Pedal Switch 

Applied/ Released

Released 

Released 

Vehicle Speed 

km/h / MPH 

0 

0 

Engine Control System (4JH1)  6E-37 

Scan Tool Parameter 

Units Displayed

Typical Data Value at 

Engine Idle 

Typical Data Value at 2000 

RPM 

Glow Relay Command 

On/Off 

Off 

Off 

Glow Indicator Lamp Command 

On/Off 

Off 

Off 

Malfunction Indicator Lamp (MIL) Command 

On/Off 

Off 

Off 

A/C Request Signal 

On/Off 

Off 

Off 

A/C Relay Command 

On/Off 

Off 

Off 

 
 

Scan Tool Data Definitions 

A list of each message displayed on the scan tool will
be explained in Engine Controls. This information will
assist in emission or driveability problems. The displays
can be viewed while the vehicle is being driven. Always
perform the Diagnosis System Check – Engine Controls
first. The Diagnostic System Check will confirm proper
system operation. 
Ignition Switch 
This parameter displays the input status of the ignition
switch to the ECM terminal (pin 39). The scan tool will
display On or Off. On indicates the ignition switch is
turned ON position. 
System Voltage 
This parameter displays the system voltage measured
by the ECM terminal (pin 3) at the voltage feed from the
ECM main relay. 
ECM Main Relay 
This parameter displays the commanded state of the
ECM main relay control circuit (pin 58). The scan tool
will display On or Off. On indicates the ECM main relay
control circuit is being grounded by the ECM, allowing
the main relay to supply voltage to the other circuits of
the ECM. Off indicates the main relay is not being
commanded On by the ECM. 
Engine Speed 
This parameter displays the speed of the crankshaft as
calculated by the ECM based on input from the
crankshaft position (CKP) sensor or camshaft position
(CMP) sensor. The scan tool will display the engine
speed in revolution per minute (RPM). 
 

 

Desired Idle Speed 
This parameter displays the idle speed requested by the 
ECM. The ECM will compensate for various engine
loads based on engine coolant temperature (ECT) and 
A/C system status. If the A/C system is activated, the 
ECM sets 100 RPM higher than normal idle speed. 
Injection Pump Speed 
This parameter displays the speed of the injection pump 
as calculated by the fuel injection pump control unit 
(PCU) based on the input from the fuel injection pump 
camshaft position (CMP) sensor. The scan tool will
display the injection pump speed in revolution per
minute (RPM). 
Accelerator Pedal Position 
This parameter displays the angle of the accelerator
pedal as calculated by the ECM using the signal from 
the accelerator pedal position (APP) sensor. The
accelerator pedal position indicated angle is a range of
values indicating a low percentage when the accelerator
pedal is not depressed to a high percentage when the
accelerator pedal is fully depressed. 
Idle Switch 
This parameter displays the input status of the idle
switch to the ECM terminal (pin 69). The Tech will
display On or Off. On indicates the accelerator pedal is
not being pushed down. Off indicates the accelerator
pedal is being depressed.