2007 ISUZU KB P190 engine mount

6E-190 Engine Control System (4JH1)
DTC P1120 (Symptom Code 1) (Flash Code 21)
Circuit Description
The accelerator pedal position (APP) sensor is mounted
on the intake throttle assembly. The engine control
module (ECM) uses the APP sensors to determine the
amount of acceleration or deceleration desired by the
person driving the vehicle via the fuel injection control.
The APP sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• APP sensor signal circuit
The ECM supplies 5 volts to the APP sensor on the 5
volts reference circuit. The ECM also provides a ground
on the low reference circuit. The APP sensor provides a
signal to the ECM on the APP sensor signal circuit,
which is relative to the position changes of the
accelerator pedal angle. The ECM monitors the
APP
sensor signal for voltages outside the normal range o
f
the APP sensor. If the ECM detects an excessively high
APP sensor signal voltage, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.

Condition for Setting the DTC
• The ECM detects that the APP sensor signal
voltage is more than 4.5 volts for 0.5 seconds.
Action Taken When the DTC Sets • The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses an engine speed substitution o
f
1400 RPM.
Condition for Clearing the MIL/DTC • The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
• A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids • If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.

DTC P1120 (Symptom Code 1) (Flash Code 21)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check-
Engine Controls? 
Go to Step 2 Go to Diagnostic
System Check-
Engine Controls
2 1. Install the scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Disconnect the accelerator pedal position (APP) sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Observe the Accelerator Pedal Position (APP) parameter with the scan tool.
Does the APP parameter less than the specified
value? 1%
Go to Step 4 Go to Step 5
4 1. Turn OFF the ignition. 2. Connect a test lamp between the low reference circuit of the APP sensor harness (pin 1 of E-22
connector) and battery voltage.
3. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 11 Go to Step 8
5 1. Turn OFF the ignition. 2. Connect a DMM between the 5 volts reference circuit of the APP sensor harness (pin 3 of E-22
connector) and a known good ground.
3. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value? 4.5 volts
Go to Step 6 Go to Step 9

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-193
DTC P1120 (Symptom Code 7) (Flash Code 21)
Circuit Description
The accelerator pedal position (APP) sensor is mounted
on the intake throttle assembly. The engine control
module (ECM) uses the APP sensors to determine the
amount of acceleration or deceleration desired by the
person driving the vehicle via the fuel injection control.
The APP sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• APP sensor signal circuit
The ECM provides 5 volts reference voltage through the
reference circuit to the APP sensor. The ECM monitors
the voltage on the 5 volts reference circuit. If the ECM
detects an excessively high APP sensor 5 volts
reference voltage, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.

Condition for Setting the DTC
• The ECM detects that the APP sensor voltage
supply circuit is more than 5.2 volts for 0.5
seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses an engine speed substitution o
f
1400 RPM.
Condition for Clearing the MIL/DTC • The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
• A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids • If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.

DTC P1120 (Symptom Code 7) (Flash Code 21)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check-
Engine Controls? 
Go to Step 2 Go to Diagnostic
System Check-
Engine Controls
2 1. Install the scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 1. Test the 5 volts reference circuit between 1the engine control module (ECM) (pin 57 of C-56
connector) and the accelerator pedal position
(APP) sensor (pin 3 of E-22 connector) for a
short to battery or ignition voltage.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 5 Go to Step 4
4 Important: Replacement ECM must be
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.
Did you complete the replacement? 

Go to Step 5 
5 1. Reconnect all previously disconnected harness
connector(s).
2. Clear the DTCs with the scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Turn ON the ignition, with the engine OFF.
5. Fully depress and release the accelerator pedal many times.
6. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition? 

Go to Step 3 Go to Step 6

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-195
DTC P1120 (Symptom Code 9) (Flash Code 21)
Circuit Description
The accelerator pedal position (APP) sensor is mounted
on the intake throttle assembly. The engine control
module (ECM) uses the APP sensors to determine the
amount of acceleration or deceleration desired by the
person driving the vehicle via the fuel injection control.
The APP sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• APP sensor signal circuit
The ECM provides 5 volts reference voltage through the
reference circuit to the APP sensor. The ECM monitors
the voltage on the 5 volts reference circuit. If the ECM
detects an excessively high APP sensor 5 volts
reference voltage, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.

Condition for Setting the DTC
• The ECM detects that the APP sensor voltage
supply circuit is less than 4.6 volts for 0.5 seconds.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses an engine speed substitution o
f
1400 RPM.
Condition for Clearing the MIL/DTC • The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
• A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids • If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Test Description
The number below refers to the step number on the
diagnostic table.
3. If the APP sensor 5 volts reference circuit between
the ECM and the sensor is normal, the sensor signal
correlation DTC P1120 (Symptom Code E) will set.

DTC P1120 (Symptom Code 9) (Flash Code 21)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check-
Engine Controls? 
Go to Step 2 Go to Diagnostic
System Check-
Engine Controls
2 1. Install the scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition. 2. Disconnect the accelerator pedal position (APP) sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Depress and release the accelerator pedal many times.
5. Monitor the DTC Information with the scan tool.
Does DTC P1120 (Symptom Code E) set, but not
DTC P1120 (Symptom Code 9)? 

Go to Step 5 Go to Step 4
4 1. Test the 5 volts reference circuit between the engine control module (ECM) (pin 57 of C-56
connector) and the APP sensor (pin 3 of E-22
connector) for the following conditions: • A short to ground
• A short to the low reference circuit
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 7 Go to Step 6

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-197
DTC P1120 (Symptom Code D) (Flash Code 21)
Circuit Description
The accelerator pedal position (APP) sensor is mounted
on the intake throttle assembly. The engine control
module (ECM) uses the APP sensors to determine the
amount of acceleration or deceleration desired by the
person driving the vehicle via the fuel injection control.
The APP sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• APP sensor signal circuit
The ECM supplies 5 volts to the APP sensor on the 5
volts reference circuit. The ECM also provides a ground
on the low reference circuit. The APP sensor provides a
signal to the ECM on the APP sensor signal circuit,
which is relative to the position changes of the
accelerator pedal angle.
The brake pedal switch is installed on the brake pedal
bracket. The brake pedal 1 switch is a normally open
type switch and the brake pedal 2 switch is a normally
closed type switch. W hen the brake pedal is pressed,
the brake pedal 1 switch signal is provided to the ECM
and the stoplights are turned ON. Then, the brake pedal
2 switch signal to the ECM is stopped (low voltage).
If the ECM detects accelerator pedal or APP senso
r
signal is stuck while brake pedal is depressed, this DTC
will set.
Condition for Running the DTC
• The ignition switch is ON.
• The engine speed is higher than 1700 RPM.
• The vehicle speed is higher than 1.5 km/h (1
MPH).
Condition for Setting the DTC
• The ECM detects APP sensor angle is stationar
y
more than 8.7%, then brake pedal is depressed fo
r
longer than 2 seconds.
Action Taken When the DTC Sets • The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses an engine speed substitution o
f
1400 RPM.
Condition for Clearing the MIL/DTC • The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
• A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids • If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
• Misadjusted brake pedal switch may set this DTC.
• Misadjusted APP sensor may set this DTC.
• Misadjusted throttle cable may set this DTC.
• A sticking or intermittently sticking the intake
throttle valve, control cable or pedal may set this
DTC.

DTC P1120 (Symptom Code D) (Flash Code 21)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check-
Engine Controls? 
Go to Step 2 Go to Diagnostic
System Check-
Engine Controls
2 1. Install the scan tool. 2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
W as DTC P0703 (Symptom Code A or B) or P1120
(Symptom Code 1, 7, 9 or E) set? 

Go to Applicable DTC Go to Step 3
3 1. Turn ON the ignition, with the engine OFF. 2. Observe the Brake Pedal 1 Switch parameter with the scan tool while fully depressing and
releasing the brake pedal.
Does the scan tool indicate Applied when the brake
pedal is applied and Released when the brake pedal
is released? 

Go to Step 9 Go to Step 4

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ISUZU KB P190 2007

6E-200 Engine Control System (4JH1)
DTC P1120 (Symptom Code E) (Flash Code 21)
Circuit Description
The accelerator pedal position (APP) sensor is mounted
on the intake throttle assembly. The engine control
module (ECM) uses the APP sensors to determine the
amount of acceleration or deceleration desired by the
person driving the vehicle via the fuel injection control.
The APP sensor has the following circuits.
• 5 volts reference circuit
• Low reference circuit
• APP sensor signal circuit
The ECM supplies 5 volts to the APP sensor on the 5
volts reference circuit. The ECM also provides a ground
on the low reference circuit. The APP sensor provides a
signal to the ECM on the APP sensor signal circuit,
which is relative to the position changes of the
accelerator pedal angle.
The idle switch is also mounted on the intake throttle
assembly. The idle switch is part of the APP senso
r
assembly. The idle switch is a normally closed type
switch. W hen the accelerator pedal is released, the idle
switch signal to the ECM is low voltage.
If the ECM detects the
APP sensor signal and the idle
switch out of correlation, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.

Condition for Setting the DTC
Either of following condition is met. • The ECM detects APP sensor angle is less than
0.35%, then the idle switch is OFF for longer than
0.6 seconds.
• The ECM detects APP sensor angle is more than
8.7%, then the idle switch is ON for longer than 0.6
seconds.
Action Taken When the DTC Sets • The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses an engine speed substitution o
f
1400 RPM.
Condition for Clearing the MIL/DTC • The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
• A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids • If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.

DTC P1120 (Symptom Code E) (Flash Code 21)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check-
Engine Controls? 
Go to Step 2 Go to Diagnostic
System Check-
Engine Controls
2 1. Turn ON the ignition, with the engine OFF. 2. Observe the Idle Switch parameter with the scan tool while depressing and releasing the
accelerator pedal.
Does the scan tool indicate OFF when the
accelerator pedal is depressed and ON when the
accelerator pedal is released? 

Go to Step 10 Go to Step 3
3 1. Turn OFF the ignition. 2. Disconnect the idle switch harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Observe the Idle Switch parameter with the scan tool while momentarily jumping 3-amp fused
jumper wire across the idle switch harness
connector between pins 1 and 2 of the E-23
connector.
Does the scan tool indicate ON when the circuit is
jumpered and OFF when the circuit is not jumpered? 

Go to Step 9 Go to Step 4

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ISUZU KB P190 2007

6E-262 Engine Control System (4JH1)
Checks Action
Additional Checks •
Electromagnetic interference (EMI) on the reference circuit can cause an engine miss
condition. The scan tool can usually detect EMI by monitoring the engine speed. A
sudden increase in speed with little change in actual engine speed change indicates that
EMI is present. If a problem exists, check routing of high voltage components, such as
fuel injection solenoid valve wiring, near the sensor circuits.
• Inspect for faulty engine mounts.
• Inspect faulty crank pulley.
• Inspect faulty generator & A/C compressor.
• Inspect the generator output voltage. Repair if less than 9 volts or more than 16 volts.
• Inspect the EGR system operating correctly.
• Inspect the A/C operation.


Cut Out, Misses
Checks Action
DEFINITION:A constant jerking that follows the engine speed, usually more pronounced as the engine load increase. The
exhaust has a steady spitting sound at idle, low speed, or hard acceleration for the fuel starvation that can cause the engine to
cut-out.
Preliminary Check • Diagnostic System Check - Engine Controls.
• Inspect that the harness connectors are correctly connected.
• Inspect the engine control module (ECM) and fuel injection pump control unit (PCU)
grounds for being clean, tight, and in their proper locations.
• Inspect the scan tool Data List in this section.
• Inspect the Service Bulletins for ECM software updates.
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool
Data List in this section.
• Use the scan tool to observe the Accelerator Pedal Position. Accelerator Pedal
Position indicating angle parameter should change linearly from 0% to 100%
according to the accelerator pedal operation.
• Inspect the crankshaft position (CKP) sensor is tight and the flywheel circumference
is not damaged.

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-271
Checks Action
Engine Mechanical Checks Inspect the engine mechanical for the following conditions. Refer to the Engine
Mechanical section.
• Inspect for poor cylinder compression. Proper compression is more than 2100 kPa
(309 psi).
• Inspect for incorrect basic engine parts such as camshaft, cylinder head, pistons,
etc.
• Inspect for any excessive oil entering combustion chamber.
Additional Checks •
Inspect the EGR system operating correctly.
• Inspect other possible causes that can make similar noise such as loose component
parts, bracket, mount and weak clutch damper spring.


Poor Fuel Economy
Checks Action
DEFINITION:Fuel economy, as measured by actual road tests and several tanks of fuel, is noticeably lower than expected.
Also, the economy is noticeably lower than it was on this vehicle at one time, as previously shown by actual road tests.
Preliminary Checks • Remove the air cleaner and check for dirt, or for air ducts being plugged or
restricted. Replace as necessary.
• Inspect the driving habits of the owner.
• Is the A/C ON full time, defroster mode ON?
• Are the tires at the correct pressure?
• Are the tire sizes changed?
• Are excessively heavy loads being carried?
• Is the acceleration too much, too often?
• Inspect for clutch slip.
• Inspect brake drag.
• Inspect dive belt tension.
• Inspect for a proper transmission shift pattern and down shift operation (A/T only).
• Inspect the fuel quality (cetane index).
• Inspect the engine oil level and quality.
• Suggest to the owner to fill the fuel tank and recheck the fuel economy.
• Suggest to the driver to read the Important Facts on Fuel Economy in the Owner
Manual.
• Inspect the odometer is correctly operated.
• Inspect the Service Bulletins for ECM software updates.
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool
Data List in this section.
• Use the scan tool to compare the Engine Coolant Temperature (ECT) with the Intake
Air Temperature (IAT) and Fuel Temperature (FT) on a cold engine condition. If the
difference among temperature reading is more than 5°C (9°F) on a cold engine,
check for high resistance on the low reference circuit and signal circuit or for a
skewed sensor.
Notice: The mass air flow (MAF) sensor is heated and as a result the IAT sensor may
indicate a higher than normal intake air temperature if the ignition switch is being ON.
FT sensor is internal to the PCU and it is part of the fuel injection pump assembly.
Fuel System Checks Inspect the fuel system for the following conditions. Refer to the Fuel System section.
• Inspect the fuel type and quality.
• Check fuel leak.
Cooling System Checks Inspect the cooling system for the following conditions. Refer to the Cooling System
Section.
• Inspect the engine coolant level.
• Inspect the engine thermostat for always being open or for the wrong heat range.
• Inspect the engine cooling fan for always being ON.

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ISUZU KB P190 2007

6E-284 Engine Control System (4JH1)
Important:
To prevent possible electrostatic discharge damage,
follow these guidelines: • Do not touch the ECM connector pins or soldered
components on the ECM circuit board.
• Do not open the replacement part package until
the part is ready to be installed.
• Before removing the part from the package,
ground the package to a known good ground on
the vehicle.
• If the part has been handled while sliding across
the seat, while sitting down from a standing
position, or while walking a distance, touch a
known good ground before installing the part.
• Charge by induction occurs when a person with
well insulated shoes stands near a highly charged
object and momentarily touches ground. Charges
of the same polarity are drained off leaving the
person highly charged with opposite polarity.
Malfunction Indicator Lamp (MIL) Operation
The malfunction indicator lamp (MIL) is located in the
instrument panel cluster (IPC). The MIL will display the
following symbols when commanded ON:



RTW 76ESH004001
The MIL indicates that an emission or performance
related fault has occurred and vehicle service is
required. The following is a list of the modes o
f
operation for the MIL: • The MIL illuminates for approximately 2 seconds
when the ignition switch is turned ON, with the
engine OFF. This is a bulb test to ensure the MIL
is able to illuminate.

•
The MIL remains illuminated after the engine is
started if the ECM detects a fault. A DTC is stored
any time the ECM illuminates the MIL due to an
emission or performance related fault.

Engine Control Component Description
Accelerator Pedal Position (APP) Sensor & Idle
Switch






RTW 66ESH001301
The accelerator pedal position (APP) sensor is mounted
on the throttle assembly. The engine control module
(ECM) uses the APP sensor s to determine the amount
of acceleration or deceleration desired by the person
driving the vehicle via the fuel injection control.
The idle switch is also mounted on the intake throttle
assembly. The idle switch is part of the APP senso
r
assembly. The idle switch is a normally closed type
switch. W hen the accelerator pedal is released, the idle
switch signal to the ECM is low voltage.








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