2007 ISUZU KB P190 EGR

Engine Management – V6 – Diagnostics Page 6C1-2–221

Step Action Yes No
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 U0101 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 Using Tech 2, attempt to communicate with the PIM.
Does the PIM failed to communicate? Refer to the 6E1
Powertrain Interface Module – V6 Go to Step 4
4 Are DTCs also set in the PIM? Refer to 6E1
Powertrain Interface Module – V6 Go to Step 5
5 Are DTCs that may trigger a fault condition in the serial data
communication circuit also set in the TCM? Refer to 7C2
Automatic
Transmission –
4L60E – Electrical Diagnosis Go to Step 6
6 Replace the TCM, refer to 7C4 Automatic Transmission – 4L60E –
On-vehicle Servicing.
W as the repair completed? Go to Step 7 —
7 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 serial data communication circuit – TCM DTCs fail
this ignition cycle? Go to Step 2 Go to Step 8
8 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.
7.63 DTC U0155 or U0423
DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC U0155 – CAN-Bus No Communication W ith Gateway
• DTC U0423 – CAN-Bus Invalid Data From Gateway
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 PIM serial data communication circuit DTC sets if the ECM detects an invalid signal from the PIM.
Conditions for Running the DTC
DTCs U0155 and U0423 run continuously when the following conditions are met:
• The engine is running.

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Engine Management – V6 – Diagnostics Page 6C1-2–222

• The ignition voltage is 10.0 – 16.0 V.
Conditions for Setting the DTC
The ECM did not receive a valid signal from the PIM within the specified time frame.
Conditions for Clearing the DTC
The PIM 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 U0155 or U0423 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 U0155, or U0423 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this Section
3 Replace the PIM. Refer to 6E1 Powertrain Interface Module – V6.
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 any of the PIM serial data communication circuit DTCs fail this
ignition cycle? Go to Step 2 Go to Step 5
5 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.

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Engine Management – V6 – Diagnostics Page 6C1-2–224

Ignition ON:
• Engine stopped, ignition in the ON position.
• Closed throttle.
• Transmission selector in the Park position (Automatic
Transmission) or Neutral (Manual Transmission.
• Engine, transmission at ambient temperature.
• Accessories are OFF.
• Brake pedal is not applied.
Engine Running
• Engine running.
• Closed throttle.
• Transmission selector in the Park position (Automatic
Transmission) or Neutral (Manual Transmission.
• Engine, transmission at normal operating temperature.
• Accessories are OFF.
• Brake pedal not applied.
NOTE
The values quoted in the following data lists are
only intended to provide the Technician with an
indication of the values to be expected.
W hen ‘F1 Data Display’ is selected, there are 12 data lists provided, that can save time when diagnosing symptomatic
conditions.
Engine Data 1
Engine Data 2
EVAP Data
Fuel Trim Data
O2 Sensor Data
TAC Data (Throttle Actuator Control)
Cooling/HVAC Data
Cruise Control Data
Electrical/Theft Data
Instrument Data
ODM Data (Output Driver Module)
Misfire Data
F2: OBD Data
In this test mode, Tech 2 displays engine management data parameters relating to the OBD (On Board Diagnostic) for
the engine being diagnosed. Refer to 8.5 OBD Data for specific detail.
F3: Snapshot
In this test mode, Tech 2 captures data before and after a snapshot triggering event that may or may not set a DTC.
F4: Actuator Test
In this test mode, Tech 2 performs software override commands to the ECM, to assist in problem isolation during
diagnostics. W hen entering this mode, there are 9 actuators that can be tested for operational integrity. The 9 tests
available are:
F0: Fuel Pump Relay Test
F1: Electronic Throttle Control Test
F2: A/C Relay Test
F3: Cooling Fan PW M
F4: Alternator L Terminal

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ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–238

B2 Average Injection Time (Bank 2) ms 0.0 1.9
Mass Air Flow Sensor V 1.0 1.1
Mass Air Flow g/s 0.00 2.92
Power Enrichment No / Yes No No
Spark Advance °CA 0 13
Calculated Throttle Position % 5 1
Vehicle Speed km/h 0 0
Volumetric Efficiency % 99 13
(1) Automatic Transmission Only (2) Manual Transmission Only
8.4 Tech 2 Data Definitions
NOTE
This listing is arranged in alphabetical order and
defines each parameter shown in the Data Lists.
A/C Cutoff Mode (Air Conditioning): This parameter displays whether the control module is commanding the A/C
compressor clutch relay OFF for a number of reasons, among which is; operating pressure outside given parameters or
throttle position at wide open throttle (W OT).
A/C Disengagement 1 – 8 History: The parameter displays the last 8 air conditioning (A/C) compressor disengages in
order from 1 to 8 with 8 being the most recent. There are 8 possible causes listed for the A/C compressor to disengage;
High Pressure, Engine Speed, Battery Voltage, Stall Prevention, Full Load, Performance, Engine Temperature or Signal
not Present. Any of these causes need to be outside calibrated values, to cause the A/C to disengage.
A/C Pressure Sensor (Air Conditioning): This parameter displays the voltage from the A/C high side pressure sensor
signal circuit to the control module.
A/C Pressure Sensor (Air Conditioning): This parameter displays the pressure in kPa from the A/C high side pressure
sensor signal circuit to the control module.
A/C Relay (Air Conditioning): This parameter displays the state of the A/C clutch relay control circuit, either as ‘ON’ or
‘OFF’.
A/C Relay Status: This parameter displays the state of the A/C request input to the control module from the heating,
ventilation, and air conditioning (HVAC) controls.
A/C Request: Represents the commanded state of the A/C clutch control relay. Clutch should be engaged when ON is
displayed.
Actual Gear: This parameter displays the transmission range input to the control module, determined directly from the
decoding of the PRNDL – A, B, C, and P inputs from the transmission internal mode switch (IMS).
Actual Gear: Based on the evaluation of the PRNDL – A, B, C, and P inputs, the ECM determines whether the
parameter is valid or invalid.
Actual Intake Camshaft Position (Bank 1 or Bank 2): This parameter displays the actual intake camshaft position in
degrees of crankshaft angle.
Alternator L Terminal Duty Cycle: This parameter displays the ECM commanded state of the voltage regulator on the
alternator, expressed as a percentage from 0 to 100.
APP Sensor 1 (Accelerator Pedal Position): This parameter displays the actual voltage on the APP sensor 1 signal
circuit as measured by the ECM, that can range from 0.9 – 4.5 volts.
APP Sensor 2 (Accelerator Pedal Position): This parameter displays the actual voltage on the APP sensor 1 signal
circuit as measured by the ECM, that can range from 0.45 – 2.25 volts.
APP Sensor 1 and 2 Correlation (Accelerator Pedal Position): This parameter displays ‘Okay’ under normal
operating conditions or ‘Fault’ if the control module detects the signal voltage from APP sensor 1 that is not in the
correct relationship to APP sensor 2.
Average Injection Time (Bank 1 or Bank 2): This parameter displays the average pulse width of the fuel injectors for
each bank of the engine as determined by the ECM.

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Engine Management – V6 – Diagnostics Page 6C1-2–239

B1/B2 S1 O2 Sensor 1 (Bank 1 or Bank 2 Sensor 1): This parameter displays the lambda output from the HO2S to the
ECM. A lambda below 1.0 indicates a rich exhaust, while a lambda above 1.0 indicates a lean exhaust.
B1/B2 S2 O2 Sensor 2 (Bank 1 or Bank 2 Sensor 2): This parameter displays the mV output from the HO2S to the
ECM. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.
B1/B2 S1 O2 Sensor Heater (Bank 1 or Bank 2 Sensor 1): This parameter displays the resistance of the sensing
element within the ECM. The front sensors are normally regulated to 80 ohms.
B1/B2 S1/S2 O2 Sensor Heater Circuit Status (Bank 1 or Bank 2 Sensor 1 or Sensor 2): The parameter displays
‘Fault’ if the oxygen sensor heater control circuit is open, shorted to ground, or shorted to voltage. The parameter
displays ‘Undefined’ until the circuit has been commanded ON.
Barometric Pressure: This parameter displays the barometric pressure in kPa. The ECM uses the barometric pressure
for fuel control to compensate for altitude differences.
Barometric Pressure: This parameter displays the barometric pressure voltage. The control module uses the
barometric pressure for fuel control to compensate for altitude differences.
Brake Lamp Switch: This parameter displays the status of the brake lamp switch. W hen the brake pedal is pressed the
switch contacts close causing the vehicles brake lamps to illuminate.
Brake Switch Signal Status: This parameter displays the position of the torque converter clutch (TCC) brake pedal
switch input to the ECM.
Calculated ECT – Closed Loop Fuel Control (Engine Coolant Temperature): This parameter displays the modelled
temperature that the control module calculates from air entering the engine, coolant temperature, and ambient air
temperature. If the actual engine coolant temperature does not reach this calculated temperature within a predetermined
amount of time, a DTC will set.
Calculated ECT – Thermostat Diagnosis (Engine Coolant Temperature): This parameter displays the modelled
temperature that the control module calculates from air entering the engine, coolant temperature, and ambient air
temperature. If the actual engine coolant temperature does not reach this calculated temperature within a predetermined
amount of time, a DTC will set.
Calculated Pedal Position: This parameter displays the angle of the accelerator pedal position (APP) as calculated by
the ECM, using the signals from the APP sensors, as a percentage of throttle opening.
Calculated Throttle Position: This parameter displays the percentage of throttle opening, based on the two TP sensor
inputs to the ECM.
Catalyst Protection Mode: This parameter displays if the control module is commanding catalytic converter protection
or not.
Catalyst Temperature (Bank 1 or Bank 2): This parameter displays the catalytic converter temperature as calculated
by the control module.
Clutch Pedal Switch: This parameter displays the state of the clutch pedal as determined by the ECM from the clutch
start switch position.
Clutch Pedal Switch: This parameter displays the state of the clutch pedal as determined by the ECM from the clutch
pedal switch.
Commanded Exhaust Camshaft Position (Bank 1 or Bank 2): This parameter displays the exhaust camshaft position
in percent of range as commanded by the control module.
Commanded Exhaust Camshaft Position (Bank 1 or Bank 2): This parameter displays the exhaust camshaft position
in crankshaft degrees, as commanded by the ECM.
Commanded Intake Camshaft Position (Bank 1 or Bank 2): This parameter displays the intake camshaft position in
crankshaft degrees, as commanded by the ECM.
Commanded B1/B2 S1 O2 Sensor Heater (Bank 1 or Bank 2 Sensor 1): This parameter displays the state of the
oxygen sensor heater control circuit, as a percentage.
Commanded B1/B2 S1 O2 Sensor Value (Bank 1 or Bank 2 Sensor 1): This parameter displays the lambda output
from the HO2S to the ECM. A lambda below 1.0 indicates a rich exhaust, while a lambda above 1.0 indicates a lean
exhaust.
Coolant Temperature: This parameter displays the temperature of the engine coolant based on input to the control
module from the engine coolant temperature (ECT) sensor.
Crank Request: This parameter displays whether the ignition switch has been cycled to the crank position, requesting
the ECM to activate the starter relay.
Cruise Control Active: This parameter displays the status of the cruise control system as determined by the ECM.

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Engine Management – V6 – Diagnostics Page 6C1-2–241

Cooling Fan Relay Circuit Status: This parameter displays the state of the fan relay control circuit. The parameter
displays ‘Fault’ if the fan relay control circuit is open, shorted to ground, or shorted to voltage. The parameter displays
‘Undefined’ until the relay control circuit has been determined as being ‘OK’.
Fuel Level: This parameter displays the amount of fuel in the fuel tank in litres, as calculated by the ECM from data
received from the fuel level sensor.
Fuel Level Sensor: This parameter displays the voltage received from the fuel level sensor in the fuel tank, by the ECM.
Fuel Pump Relay Circuit Status: This parameter displays the state of the fuel pump relay control circuit. The
parameter displays ‘Fault’ if the fuel pump relay control circuit is open, shorted to ground, or shorted to voltage. The
parameter displays ‘Undefined’ until the relay control circuit has been determined as being ‘OK’.
Fuel Pump Relay: This parameter displays the ECM commanded state of the fuel pump relay control circuit.
Fuel Trim Learn: This parameter displays ‘Enabled’ when conditions are appropriate for enabling long term fuel trim
corrections. This indicates that the long term fuel trim is adapting continuing amounts of short term fuel trim. If Tech 2
displays ‘Disabled’, then long term fuel trim will not respond to changes in short term fuel trim.
Ignition Accessory Signal: This parameter displays ‘On’ when the control module detects a voltage at the
ignition ‘ACC’ terminal, X1-4 of the ignition switch.
Ignition On Signal: This parameter displays ‘On’ when the control module detects a voltage at the ignition ‘IGN’
terminal X1-3 of the ignition switch.
Initial Brake Apply Signal: This parameter displays the status of the brake lamp switch. Before the cruise control can
be activated, this switch contact must be open circuit when the brake pedal is pressed.
Injection Time Cylinder 1 – 6: This parameter displays the amount of fuel injector On-time or pulse width as
commanded by the ECM.
Intake Air Temperature: This parameter displays the temperature of the air entering the air induction system based on
input to the ECM from the intake air temperature (IAT) sensor.
Knock Sensor Signal (Bank 1 or Bank 2): This parameters displays the voltage input to the control module from the
knock sensor (KS).
Knock Retard: This parameter indicates the amount of spark advance in crankshaft degrees, that the ECM removes
from the ignition control (IC) spark advance in response to the signal from the knock sensors.
Knock Retard Cylinder 1 – 6: This parameter displays the knock retard as commanded by the ECM for cylinders 1-6.
Each cylinder is controlled individually based on both knock sensor signal inputs.
Loop Status B1S1 / B2S1 (Bank 1 or Bank 2 Sensor 1): This parameter displays the state of the fuel control system
as commanded by the ECM. ‘Closed’ Loop operation indicates that the ECM is controlling the fuel delivery based on the
oxygen sensors input signal. In ‘Open’ Loop operation the ECM ignores the oxygen sensor input signal and bases the
amount of fuel to be delivered on other sensor inputs.
LTFT Idle/Deceleration (Bank 1 or Bank 2) (Long Term Fuel Trim): This parameter displays the commanded Long
Term Fuel Trim correction by the ECM for bank 1 or bank 2 for idle and deceleration conditions.
LTFT Cruise/Acceleration (Bank 1 or Bank 2) (Long Term Fuel Trim): This parameter displays the commanded Long
Term Fuel Trim correction by the ECM for bank 1 or bank 2 for cruise and acceleration conditions.
Malfunction Indicator (MI): This parameter displays the commanded (‘On, ‘Off’ or ‘Flashing’) state of the malfunction
indicator lamp (MIL) control circuit by the ECM.
Malfunction Indicator (MI) Circuit Status: This parameter displays the state of the MIL control circuit. The parameter
displays ‘Fault’ if the MIL control circuit is open, shorted to ground, or shorted to voltage. This parameter displays
‘Undefined Status’ until the circuit has been determined as being ‘OK’.
Mass Air Flow: This parameter displays the measured quantity (g/s) of air flowing into the engine during all operating
conditions.
Mass Air Flow Sensor: This parameter displays the signal voltage from the mass air flow (MAF) sensor to the ECM.
Misfire Current Cyl. #1 – #6: Tech 2 displays a range of 0 – 200 counts. This parameter displays the number of
misfires that have been detected during the last 200 cylinder firing events. The counters may normally display some
activity, but the activity should be nearly equal for all of the cylinders, and in low numbers.
Misfire History Cyl. #1 – #6: Tech 2 displays a range of 0 – 65,535 counts. The misfire history counters display the total
level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity
until a misfire DTC P0300 has become active. The misfire history counters will update every 200 cylinder firing events.
Oil Level: W hen the ECM receives information from the engine oil level switch, where the engine oil level is within
preset parameters, Tech 2 will display ‘Normal’. If not within preset parameters, the display will show ‘Low’.

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Engine Management – V6 – Diagnostics Page 6C1-2–242

Oil Temperature Sensor: This parameter displays the engine oil temperature in degrees C.
Power Enrichment: This parameter displays the status of the operating mode of the ECM used to increase fuel delivery
during certain acceleration conditions.
Reduced Engine Power: This parameter displays when the ECM is commanding reduced engine power due to a
throttle actuator control (TAC) system condition.
Requested Torque: This parameter displays the calculated amount torque requested of the ECM by the Transmission
Control Module (TCM).
Short Term Fuel Trim (Bank 1 or Bank 2): This parameter displays the short-term correction to the fuel delivery by the
ECM in response to oxygen sensor 1 or 2. If the oxygen sensor indicates a lean air/fuel mixture, the control module will
add fuel, increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control
module will reduce fuel decreasing the short term fuel trim below 0.
Spark Advance: This parameter displays the amount of spark advance the ECM is commanding on the ignition control
circuits. The ECM determines the desired advance.
Starter Relay: This parameter displays the Em’s commanded state of the starter motor relay control circuit.
Starter Relay Circuit Status: This parameter displays the state of the starter relay control circuit. The parameter
displays ‘Fault’ if the starter relay control circuit is open, shorted to ground, or shorted to voltage. The parameter
displays Undefined Status’ until the circuit has been determined as being ‘OK’. This parameter may not change if Tech 2
is used to command the relay control circuit ON.
Start Up ECT (Engine Coolant Temperature): This parameter displays the temperature of the engine coolant on start
up based on input to the ECM from the ECT sensor.
Start Up IAT (Intake Air Temperature): This parameter displays the temperature of the intake air at start in the air
induction system based on input to the ECM from the IAT sensor.
Time Since Engine Off: This parameter displays the amount of time (hours:minutes:seconds) that has elapsed since
the engine was last cycled OFF.
Total Fuel Trim (Bank 1 or Bank 2): This parameter displays the overall fuel trim from the idle/decel cell and the
cruise/accel cell.
Total Misfire: This parameter displays the total number of cylinder firing events that the control module detected as
misfires for the last 200 crankshaft revolution sample period.
TP Sensor 1 (Throttle Position): This parameter displays the actual voltage on the TP sensor 1 signal circuit as
measured by the ECM.
TP Sensor 1 Learned Lower Position (Throttle Position): This parameter displays the learned minimum value of TP
sensor 1 as recorded by the ECM during the last learn procedure.
TP Sensor 2 (Throttle Position): This parameter displays the actual voltage on the TP sensor 2 signal circuit as
measured by the ECM.
TP Sensor 2 Learned Lower Position (Throttle Position): This parameter displays the learned minimum value of TP
sensor 2 as recorded by the ECM during the last learn procedure.
TP Sensor 1-2 Correlation (Throttle Position): This parameter displays ‘Fault’ when the ECM detects that TP sensor 1
voltage signal is not within the correct relationship to TP sensor 2. Tech 2 displays ‘Okay’ under normal operating
conditions.
Transmission Gear: This parameter displays the position of the transmission gear selector that is transmitted over the
serial data circuit from the TCM.
Transmission Gear Selector Signal: This parameter displays the position of the transmission gear selector that is
transmitted over the serial data circuit from the TCM.
Vehicle Speed: This parameter displays the speed of the vehicle as calculated by the TCM from information received
from the vehicle speed sensor (VSS).
Volumetric Efficiency: This parameter displays the volumetric efficiency of the engine as calculated by the control
module.
8.5 OBD Data
Typical Values Tech 2 Display Units Displayed
Ignition On Engine Running
B1S1 O2 Sensor (Bank 1 Sensor 1) mA 0.008 0

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Powertrain Interface Module – V6 Page 6E1–7


Figure 6E1 – 1
Legend
1 CAN Bus Lines
2 Cut-off Resistors (resistors are integrated into the PIM and ECM)
3 Powertrain Interface Module (PIM) 4 Transmission Control Module (TCM)
5 Engine Control Module (ECM)
Serial Data
W hen information is sent from one control module to another via the serial data bus, the information sent is known as
serial data. Serial data in its electronic form, is made up of rapidly changing high to low voltage pulses strung together.
Each string of voltage pulses represents a message.
• GM LAN serial data has two data lines along which serial data is sent. These lines are known as CAN_HI and
CAN_LO.
• CAN HI – The CAN HI data line is a 3.6 V data line that toggles the voltage between 2.5 V and 3.6 V
(referenced to ground). W hen there is no communication on the CAN HI data line, the system voltage
is 2.5 V.
• CAN LO – The CAN LO data line is a 2.5 V data line that toggles the voltage between 2.5 V and 1.4 V
(referenced to ground). W hen there is no communication on the CAN LO data line, the system voltage
is 2.5 V.
Serial Data Communication Protocols
General Motors Local Area Network (GM LAN)
GM LAN is a communication protocol based on the Controller Area Network physical layer. The main difference between
GM LAN and CAN is the way in which the messages are structured.

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