Circuit ISUZU KB P190 2007 Workshop Repair Manual
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Page 1912 of 6020

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-295
Circuit/ System Testing DTC P2229
13Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step Action Value(s) Yes No
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 a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Observe the Barometric Pressure (BARO) Sensor parameter with a scan tool.
Is the BARO Sensor parameter more than the
specified value? 4.3 volts
Go to Step 3 Go to Diagnostic
Aids
3 Monitor the DTC Information with a scan tool.
Is DTC P0653 also set? —
Go to Step 4 Go to Step 5
4 1. Turn OFF the ignition.
2. Disconnect the BARO sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
Is the BARO Sensor parameter less than the
specified value? 0.1 volts
Go to DTC P0653 Go to Step 7
5 1. Turn OFF the ignition.
2. Disconnect the BARO sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
Is the BARO Sensor parameter less than the
specified value? 0.1 volts
Go to Step 6 Go to Step 7
6 Connect a test lamp between the low reference
circuit (pin 1 of E-40) and battery voltage.
Does the test lamp illuminate? —
Go to Step 9 Go to Step 8
7 Important:
The BARO sensor may be damaged if
the sensor signal circuit is shorted to a voltage
source.
1. Test the signal circuit between the ECM (pin 18 of E-90) and the BARO sensor (pin 2 of E-
40) for the following conditions:
• A short to battery or ignition voltage
• A short to any 5 volts reference
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 12
8 1. Test the low reference circuit between the
ECM (pin 17 of E-90) and the BARO sensor
(pin 1 of E-40) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 13 Go to Step 10
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ISUZU KB P190 2007
Page 1914 of 6020

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-297
DTC P2621 or P2622 (Flash Code 94)
Circuit Description
The accelerator pedal position (APP) sensor is
mounted on the accelerator pedal control assembly.
The analogue APP signals are converted by the ECM
into a pulse width modulation (PWM) signal. This
converted signal is sent from the ECM to the TCM to
determine appropriate shift points depending on the
accelerator pedal pressing amount. If the ECM detects
an improper voltage level on the APP PWM signal
circuit, DTC P2621 or P2622 will set.
Condition for Running the DTC • The battery voltage is more than 9 volts.
• The ignition switch is ON.
Condition for Setting the DTC • The ECM detects a low voltage condition on the APP PWM signal circuit for longer than 3 seconds.
(DTC P2621) • The ECM detects a high voltage condition on the
APP PWM signal circuit for longer than 3 seconds.
(DTC P2622)
Action Taken When the DTC Sets • The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P2621
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 a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with a scan tool.
Does the DTC fail this ignition? —
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition.
2. Back probe a DMM between the accelerator pedal position (APP) signal circuit of the TCM
harness connector (pin 16 of C-94) and a
known good ground.
3. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value? 10.0 volts
Go to Step 6 Go to Step 4
4 Is the DMM voltage more than the specified value
at Step 3? 2.0 volts
Go to Step 7 Go to Step 5
5 Repair the short to ground between the ECM (pin
56 of C-58) and the TCM (pin 16 of C-94).
Did you complete the repair? —
Go to Step 11
—
61. Test the signal circuit between the ECM (pin
56 of C-58) and the TCM (pin 16 of C-94) for
an open circuit or high resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 8
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Page 1915 of 6020

6E-298 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
Circuit/ System Testing DTC P2622
71. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Inspect for an intermittent and for a poor connection at the harness connector of the
TCM (pin 16 of C-94).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 9
8 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor connection at the harness connector of the
ECM (pin 56 of C-58).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 10
9 Important:
Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.
Did you complete the replacement? —
Go to Step 11
—
10Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 11
—
111. Reconnect all previously disconnected
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition? —
Go to Step 3 Go to Step 12
12 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No
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 a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Monitor the DTC Information with a scan tool.
Does the DTC fail this ignition? —
Go to Step 3 Go to Diagnostic
Aids
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Page 1916 of 6020

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-299
31. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Connect a test lamp between the accelerator pedal position (APP) signal circuit of the TCM
harness connector (pin 16 of C-94) and a
known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? —
Go to Step 4 Go to Step 5
4 1. Test the signal circuit between the ECM (pin
56 of C-58) and the TCM (pin 16 of C-94) 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 7 Go to Step 6
5 Important:
Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.
Did you complete the replacement? —
Go to Step 7
—
6Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 7
—
71. Reconnect all previously disconnected
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition? —
Go to Step 3 Go to Step 8
8 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No
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Page 1917 of 6020

6E-300 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
DTC U0001 or U0101 (Flash Code 84 or 85)
Circuit Description
The ECM, the transmission control module (TCM), the
immobilizer control unit (ICU), the data recording
module (DRM), instrument panel (IP) cluster and scan
tool communicate control and diagnostic information
via a controller area network (CAN) communication
bus. The ECM monitors CAN operational status by
expecting a constant flow of messages from the TCM,
ICU, DRM and IP cluster. If the ECM fails to send or
receive an expected message from the TCM, ICU,
DRM and IP cluster, DTC U0001 or U0101 will set
depending on what communication is lost.
Condition for Running the DTC • The battery voltage is more than 9 volts.
• The ignition switch is ON.
Condition for Setting the DTC • The ECM detects that the CAN Bus OFF status. (DTC U0001)
• The ECM detects that the CAN Bus messages from the TCM are not being received. (DTC
U0101) Action Taken When the DTC Sets
• The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
• The ECM inhibits cruise control.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A.
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
Notice: • If the TCM has DTCs set, clear the DTCs in the TCM first.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC U0001 or U0101
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 Refer to Scan Tool Does Not Communicate with
The CAN Device in this section.
Did you complete the action? —
Go to Step 3
—
31. Reconnect all previously disconnected
harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 4
4 Observe the DTC information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
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Page 1918 of 6020

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-301
DTC U0167 (Flash Code 177)
Circuit Description
The ECM communicates with the immobilizer control
unit (ICU) to execute immobilizer function. The ECM
sends request signal to the ICU. The ECM receives
response signal from the ICU. Both communication
signals are carried out via a controller area network
(CAN) communication bus. If the ECM does not detect
a response signal from the ICU, this DTC will set.
Condition for Setting the DTC • The ECM does not receive an immobilizer response signal from the ICU.
Action Taken When the DTC Sets • The ECM illuminates the SVS lamp when the diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 Specification) • The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the SVS Lamp/ DTC - Type C. (Euro 4
Specification)
• Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
• Electromagnetic interference may affect intermittent condition.
• Any communication fault with the ICU may set this DTC.
Circuit/ System Testing DTC U0167
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 a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with a scan tool.
Is DTC U0001 also set? —
Go to DTC U0001 Go to Step 3
3 Attempt to communicate with the immobilizer
control unit (ICU) via the Immobilizer Data table.
Does the scan tool communicate with the ICU? —
Go to Step 4 Go to Diagnostic
System Check - Immobilizer Controls
4 Monitor the immobilizer DTC Information with a
scan tool.
Does the immobilizer DTCs fail this ignition which
begin with B or U? —
Go to Applicable
DTC in Immobilizer
Section Go to Step 5
5 Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 6
—
61. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 7
7 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
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Page 1919 of 6020

6E-302 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
EGR Control System Check
Description
The EGR system recirculates a part of exhaust gas
back into the intake manifold, which results in reducing
NOx emissions. The EGR control system uses an
electronic control system to ensure both driveability
and low emission. A control current from the ECM
operates a solenoid to control the lift amount of EGR
valve. Also, an EGR position sensor is provided at the
rear of the solenoid to feed actual valve lift amount
back to the ECM for more precision control.
The EGR control starts when the conditions for engine
speed, engine coolant temperature, intake air
temperature and barometric pressure are satisfied.
Then, the valve opening is calculated according to the
engine speed, and target fuel injection quantity. Based
on this valve opening, the drive duty of the solenoid is
determined and the valve is driven accordingly. The
intake throttle valve is provided to adequate intake
manifold depression to ensure EGR gas flow. EGR Control Operation
• The engine coolant temperature (ECT) is between 5°C (41 °F) and 100 °C (212 °F).
• The intake air temperature (IAT) is more than 5 °C
(41 °F).
• The barometric pressure (BARO) is more than 90kPa (13psi).
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing EGR Control System Check
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 a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with a scan tool.
Are any DTCs set in which the “Action Taken When
the DTC Sets” under that particular code states,
“The ECM inhibits EGR control”? —
Refer to Applicable DTC Go to Step 3
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Page 1921 of 6020

6E-304 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
6Notice:
If the intake throttle solenoid is
commanded OFF, Intake Throttle Position
parameter indicates over 100%.
Observe the Desired Intake Throttle Position and
Intake Throttle Position parameter with a scan tool.
Does the Intake Throttle Position parameter follow
within the specified value? ±
5%
Go to Step 7 Go to Step 10
7 1. Perform the Intake Throttle Solenoid Control
with a scan tool several times.
2. Command the Desired Intake Throttle Position Increase and Decrease while observing the
Intake Throttle Position.
Does the Intake Throttle Position parameter follow
within the specified value quick enough? ±
5%
System OK Go to Step 10
8 1. Remove the EGR valve assembly from the
engine.
2. Inspect the EGR valve for the following conditions:
• Restricted EGR valve by foreign materials
• Excessive deposits at valve
• Bent valve shaft
3. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 14 Go to Step 9
9 1. Turn OFF the ignition.
2. Disconnect the EGR valve harness connector.
3. Inspect for an intermittent, for poor connections and corrosion at the harness
connector of the EGR valve (pins 1, 2, 3, 4
and 6 of E-71).
4. Disconnect the ECM harness connector.
5. Inspect for an intermittent, for poor connections and corrosion at the harness
connector of the ECM (pins 30, 31, 32, 62 and
63 of E-90).
6. Test for high resistance on each circuit.
7. Repair the connection(s) or circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 14 Go to Step 12
10 1. Remove the intake duct that is connected to
the intake throttle valve.
2. Inspect the intake throttle valve for the following conditions:
• Restricted intake throttle valve by foreign materials
• Excessive deposits at throttle bore
• Bent butterfly valve
Notice: Replace the intake throttle valve is there is
any sticking
3. Repair or replace as necessary.
Did you find and correct the condition? —
Go to Step 14 Go to Step 11
Step
Action Value(s)Yes No
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Page 1922 of 6020

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-305
111. Turn OFF the ignition.
2. Disconnect the intake throttle valve harness connector.
3. Inspect for an intermittent, for poor connections and corrosion at the harness
connector of the intake throttle valve (pins 1,
2, 3, 5 and 6 of E-38).
4. Disconnect the ECM harness connector.
5. Inspect for an intermittent, for poor connections and corrosion at the harness
connector of the ECM (pins 35, 36, 55, 56 and
57 of E-90).
6. Test for high resistance on each circuit.
7. Repair the connection(s) or circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 14 Go to Step 13
12 Replace the EGR valve. Refer to EGR valve
Replacement.
Did you complete the replacement? —
Go to Step 14
—
13Replace the intake throttle valve. Refer to Intake
Throttle Valve Replacement.
Did you complete the replacement? —
Go to Step 14
—
14Reconnect all previously disconnected components
or harness connector(s).
Did you complete the action? —
Go to Step 2
—
Step Action Value(s)Yes No
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Page 1923 of 6020

6E-306 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
Glow Control System Check
Description
The glow control system consists of the ECM, the glow
relay, the glow indicator lamp and glow plugs. The glow
control system is operated when the engine coolant
temperature is low, which allows easier engine starting.
The ECM commands the glow relay ON for a certain
length of time at ignition switch is ON with engine OFF.
In after glow phase, the glow plugs remain energized
for a certain period with engine run.
Glow Control Operation • The glow indicator lamp illuminates between 0.5 seconds to 7 seconds depending upon the engine
coolant temperature. • The pre glow control system operates when the
engine coolant temperature is less than 30 °C
(86 °F).
• The after glow control system operates when the engine coolant temperature is less than 60 °C
(140 °F).
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing Glow Control System Check (1 of 2)
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 a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with a scan tool.
Is DTC P0117, P0118 or P0380 set? —
Refer to Applicable DTC Go to Step 3
3 Notice:
If no glow indicator lamp is equipped, skip
to Step 3.
1. Verify whether the instrument panel (IP) cluster is operational.
2. Perform the Glow Plug Lamp Control with a scan tool.
3. Command the lamp ON and OFF.
Does the glow indicator lamp turn ON and OFF
with each command? —
Go to Step 4 Go to 2 of 2 Step 1
4 1. Turn OFF the ignition.
2. Make sure the metal bus bar that connects switched battery voltage supply terminal (E-
49) and all glow plugs is secured tightly.
3. Turn ON the ignition, with the engine OFF
4. Connect a test lamp between the metal bus bar (glow plug power supply E-49 terminal)
and a known good ground.
5. Perform the Glow Relay Control with a scan tool.
6. Command the relay ON while observing the test lamp.
Does the test lamp turn ON only when commanded
ON? —
Go to Step 5 Go to Step 6
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