2007 ISUZU KB P190 EGR

Engine Management – V6 – Diagnostics Page 6C1-2–143

• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
4 Test signal circuit of the EOP sensor. This circuit should display a voltage within the specified range.
5 Measures the integrity of the EOP sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.
P0521 to P0523 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section
2 1 Switch off the ignition for 30 seconds.
2 Operate the vehicle within the conditions for running the DTC.
3 Using Tech 2, select the DTC display function.
Does DTC P0521, P0522 or P0523 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 1 Switch off the ignition.
2 Disconnect the EOP sensor wiring connector.
3 Switch on the ignition with the engine not running.
4 Using a digital multimeter, measure the voltage between the EOP sensor 5 V reference circuit and the ECM housing.
Does the multimeter display 4.8 – 5.2 V? Go to Step 4 Go to Step 6
4 1 Connect a 3 A fused jumper wire between the EOP sensor 5 V
reference circuit and the EOP sensor signal circuit.
2 Switch on the ignition with the engine not running.
3 Using Tech 2, observe the EOP sensor parameter.
Does Tech 2 display 780 – 980 kPa? Go to Step 5 Go to Step 7
5 1 Switch off the ignition.
2 Remove ECM / TCM Fuse 29 from the engine compartment fuse and relay panel assembly.
3 Using a digital multimeter, measure the resistance between the EOP sensor low reference circuit and the ECM housing.
NOTE
Install the ECM Fuse 29 to the engine compartment fuse
and relay panel assembly after completing this test.
Does the multimeter display 5 Ω? Go to Step 9 Go to Step 8
6 Test the EOP sensor 5 V reference circuit for an open, short to
ground or high resistance fault condition. Refer to 8A Electrical - Body
and Chassis for information on electrical fault diagnosis.
W as any fault found and rectified? Go to Step 11 Go to Step 10
7 Test EOP sensor signal circuit for short to ground fault condition.
Refer to 8A Electrical - Body and Chassis for information on electrical
fault diagnosis.
W as any fault found and rectified? Go to Step 11 Go to Step 10

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Engine Management – V6 – Diagnostics Page 6C1-2–145

An A/C refrigerant pressure sensor circuit DTC sets if the ECM detects the A/C pressure sensor signal is not within the
specified range for 3 seconds.
Conditions for Running the DTC
DTC P0532 and P0533 run continuously when the engine is running or when the A/C is switched on.
Conditions for Setting the DTC
DTC P0532
The A/C refrigerant pressure signal voltage is less than 0.2 V for longer than 3 seconds.
DTC P0533
The A/C refrigerant pressure signal voltage is greater than 4.9 V for longer than 3 seconds.
Conditions for Clearing the DTC
The A/C refrigerant pressure sensor circuit DTCs are Type C DTCs. Refer to 1.4 Diagnostic Trouble Codes in this
Section, for action taken when Type C DTC sets and conditions for clearing Type C DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the A/C Refrigerant Pressure Sensor
operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• The A/C refrigerant pressure sensor circuit diagnostic table is developed with the assumption the A/C refrigerant
system is functioning correctly. Therefore, rectify any A/C refrigerant system fault conditions before proceeding
with this diagnostic procedure.
− An A/C refrigerant low-pressure fault condition may cause DTC P0532 to set.
− An A/C refrigerant high-pressure fault condition may cause DTC P0533 to set.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Determines if there is an A/C refrigerant system fault condition.
6 Measures the integrity of the A/C Refrigerant Pressure Sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.
DTC P0532 or P0533 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section
2 Test the A/C refrigerant system. Refer to 2A Heater and Air-
conditioning.
W as any fault found and rectified? Go to Step 12 Go to Step 3

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ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–149

Step Action Yes
No
9 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 30 seconds.
3 Start the engine.
4 Operate the vehicle within the conditions for running the DTC.
Does any of the ECM system voltage DTCs fail this ignition cycle? Go to Step 2 Go to Step 10
10 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs? Go to the
appropriate DTC
Table in this Section System OK
When all diagnosis and repairs are completed, check the system for correct operation.
7.34 DTC P0601, P0602, P0604 or P0606
DTC Description
This diagnostic procedure supports the following DTCs:
• DTC P0601 – Replace Electronic Control Unit (ECU)
• DTC P0602 – Program Electronic Control Unit (ECU)
• DTC P0604 – Replace Electronic Control Unit (ECU)
• DTC P0606 – Replace Electronic Control Unit (ECU)
Circuit Description
The engine control module (ECM) is the control centre of the engine management system. The programming and
calibration needed by the ECM to control the functionality of the engine management system are stored in the ECM read
only memory (ROM).
An ECM internal circuit, programming or memory fault DTC sets if there is an internal microprocessor integrity fault
condition with the ECM or if the ECM is not programmed.
Conditions for Running the DTC
DTC P0601
Runs once when the checksum calculation at power down is completed in the last ignition cycle.
DTC P0602 and P0606
Runs continuously when the ignition is switched on with the engine not running.
DTC P0604
Runs once when the read / write test at power-down is completed in the last ignition cycle.
Conditions for Setting the DTC
DTC P0601
The ECM detects an incorrect ROM checksum for greater than 30 seconds.
DTC P0602
The ECM programming is incomplete.
DTC P0604
The ECM detects an error in the RAM for 6 seconds.

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Engine Management – V6 – Diagnostics Page 6C1-2–182

• The APP sensor 1 signal voltage increases from 1 V at rest position to greater than 4 V when the accelerator
pedal is fully depressed.
• The APP sensor 2 signal voltage increases from 0.5 V at rest position to greater than 2 V when the accelerator
pedal is fully depressed.
The ECM monitors and evaluates the APP sensors signal voltage along with other sensor inputs to determine the
desired throttle opening. An APP sensor circuit DTC sets if the signal voltage of the APP sensor is outside the
predetermined range.
Conditions for Running the DTC
DTC P2122, P2123, P2127, P2128 and P2138 runs continuously once the following conditions are met:
• The ignition is switched on.
• The ignition voltage is greater than 7 V.
Conditions for Setting the DTC
DTC P2122
The ECM determines the APP sensor 1 signal voltage is less than 0.84 V.
DTC P2123
The ECM determines the APP sensor 1 signal voltage is greater than 4.82 V.
DTC P2127
The ECM determines the APP sensor 2 signal voltage is less than 0.66 V.
DTC P2128
The ECM determines the APP sensor 2 signal voltage is greater than 4.82 V.
DTC P2138
The ECM detects the difference between the APP sensor 1 and sensor 2 signal voltage is greater than the
predetermined value.
Conditions for Clearing DTC
The APP sensor circuit DTCs are Type ‘A’ DTCs. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action
taken when a Type ‘A’ DTC sets and conditions for clearing Type ‘A’ DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the APP sensor operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 Tests the APP sensor internal circuits throughout its range of motion. If the DTC fails while performing this test, there is an internal fault condition in the APP sensor internal circuitry.
5 Measures the integrity of the TP sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.

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Engine Management – V6 – Diagnostics Page 6C1-2–206

• The engine is running.
Conditions for Setting the DTC
DTC P2227
The ECM detects the BARO pressure changed greater than 5 kPa within 20 seconds or the BARO pressure changed
greater than 30 kPa since the last ignition cycle.
DTC P2228
The ECM detects the BARO sensor signal voltage is less than 0.20 V.
DTC P2229
The ECM detects the BARO sensor signal voltage is greater than 4.8 V for longer than 2.0 seconds.
Conditions for Clearing DTC
The BARO pressure sensor circuit DTCs are Type ‘B’ DTC. Refer to 1.4 Diagnostic Trouble Codes in this Section, for
action taken when a Type ‘B’ DTC sets and conditions for clearing Type ‘B’ DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the BARO Sensor operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
4 Test signal circuit of the BARO sensor. This circuit should display a voltage within the specified range.
5 Measures the integrity of the TP sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.
DTC P2227 P2228 or P2229 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section
2 1 Switch off the ignition for 30 seconds.
2 Operate the vehicle within the conditions for running the DTC.
3 Using Tech 2, select the DTC display function.
Does DTC P2227, P2228 or P2229 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC

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ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–218

6 1 Test the pump current circuit of the HO2S for an
open. Refer to 8A Electrical-Body and Chassis.
Did you find and correct the condition? —
Go to Step 11 Go to Step 8
7 1 Test for an intermittent and for a poor connection
at the appropriate HO2S. Refer to 8A Electrical-
Body and Chassis.
Did you find and correct the condition? —
Go to Step 11 Go to Step 9
8 1 Test for an intermittent and for a poor connection
at the engine control module (ECM). Refer to 8A
Electrical-Body and Chassis.
Did you find and correct the condition? —
Go to Step 11 Go to Step 10
9 1 Replace the HO2S. Refer to 6C1-3 Engine
Management – V6 – Service Operations.
Did you complete the replacement? —
Go to Step 11 —
10 1 Replace the ECM. Refer to 6C1-3 Engine
Management –V6 – Service Operations for
details on replacing the ECM.
Did you complete the replacement? —
Go to Step 11 —
11 1 Use Tech 2 to clear the DTCs.
2 Turn OFF the ignition for 30 seconds.
3 Start the engine.
4 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 12
12 1 Using Tech 2, select the DTC display function.
Does Tech 2 display any DTCs? —
Go to the
appropriate DTC Table in this Section System OK
When all diagnosis and repairs are completed, clear all DTCs and verify correct operation
7.61 DTC U0001
DTC Descriptor
This diagnostic procedure supports DTC U0001 – No Communication with CAN-Bus (High Speed).
Circuit Description
The engine control module (ECM) communicates directly with the control modules connected to the GM LAN serial data
communication circuit through the GM LAN protocol.
However, the immobiliser control unit (ICU) communicates with the ECM using the keyword 2000 protocol. Since the GM
LAN and keyword 2000 protocols are not compatible, a powertrain interface module (PIM) is integrated into the serial
data system to serve as a gateway. This gateway allows communication between the two protocols. Refer to 6E1
Powertrain Interface Module – V6 for further information on the GM LAN serial data communication circuit.
DTC U0001 sets if the ECM detects a fault condition in the serial data communication circuit.
Conditions for Running the DTC
DTC U0001 runs continuously when the following conditions are met:
The ignition voltage is 10.0 – 16.0 V.
The vehicle power mode requires serial data communication.

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Engine Management – V6 – Diagnostics Page 6C1-2–219

Conditions for Setting the DTC
The ECM detects a specified number of transmitted messages are not valid.
Conditions for Clearing the DTC
The Serial Data Communication Circuit DTCs are Type ‘C’ DTCs. Refer to 1.4 Diagnostic Trouble Codes in this
Section, for action taken when a Type ‘C’ DTC sets and conditions for clearing Type ‘C’ DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the ECM operation.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following number refers to the step numbers in the diagnostic table:
1 The following tests are included in the Diagnostic System Check.
• Tests the integrity of the GM LAN serial data communication circuit.
• Tests for fault conditions on the vehicle immobiliser system stored in the ICU.
DTC U0001 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section
2 1 Switch off the ignition for 30 seconds.
2 Operate the vehicle within the conditions for running the DTC.
3 Using Tech 2, select the DTC display function.
Does DTC U0001 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 4 —
4 1 Using Tech 2, clear the DTCs.
2 Switch off the ignition for 30 seconds.
3 Start the engine.
4 Operate the vehicle within the conditions for running the DTC.
Does DTC U0001 fail this ignition cycle? Go to Step 2 Go to Step 5
5 Using Tech 2, select the DTC display function.
Are there any DTCs displayed? Go to the
appropriate DTC
Table in this Section System OK
When all diagnosis and repairs are completed, check the system for correct operation.

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Engine Management – V6 – Diagnostics Page 6C1-2–220

7.62 DTC U0101
DTC Description
This diagnostic procedure supports the following DTC:
• DTC U0101 – CAN-Bus No Communication W ith TCM (Transmission Control Module)
Circuit Description
The Engine Control Module (ECM) communicates directly with the control modules connected to the GM LAN serial data
communication circuit through the GM LAN protocol.
However, the immobiliser control unit (ICU) communicates with the ECM using the keyword 2000 protocol. Since the GM
LAN and keyword 2000 protocols are not compatible, a powertrain interface module (PIM) is integrated into the serial
data system to serve as a gateway. This gateway allows communication between the two protocols. Refer to 6E1
Powertrain Interface Module – V6 for further information on the GM LAN serial data communication circuit.
A serial data communication circuit – TCM DTC sets if the ECM detects an invalid signal from the TCM.
Conditions for Running the DTC
DTC U0101 runs continuously when the following conditions are met:
• The ignition is on for longer than 3 seconds.
• The ignition voltage is 10.0 – 16.0 V.
Conditions for Setting the DTC
The ECM did not receive a valid signal from the TCM within the specified time frame.
Conditions for Clearing the DTC
This Serial Data Communication Circuit DTC is a Type C DTC. Refer to 1.4 Diagnostic Trouble Codes in this Section,
for action taken when a Type C DTC sets and the conditions required for clearing Type C DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the ECM operation.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following number refers to the step numbers in the diagnostic table:
1 The following tests are included in the Diagnostic System Check.
• Tests the integrity of the GM LAN serial data communication circuit.
• Tests for fault conditions on the vehicle immobiliser system stored in the ICU.
DTC P0864 and U0101 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section

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