2007 ISUZU KB P190 Circuit

Engine Management – V6 – General Information Page 6C1-1–29

LSU 4.2 Wide-band Planar Heated Oxygen Sensors
The LSU 4.2 wide-band planar heated oxygen sensors have
six wires:
• The internal heater element supply, which has 12 V
continually applied whenever the ignition is on.
• Heater element ground – The ECM applies pulse
width modulated (PW M) ground to the HO2S heater
control circuit to control the rate at which the sensor
heats up. This reduces the risk of the sensor being
damaged from heating up too quickly under certain
conditions such as extreme cold temperatures. Once
the sensor has reached the desired operating
temperature, the ECM will monitor and continue to
maintain the sensor temperature.
• Output voltage.
• Sensor ground.
• Trim current.
• Pumping current.
Legend
1 Measuring Cell (Nernst cell and pump cell)
2 Double Protective Tube
3 Seal Ring
4 Seal Packing
5 Sensor Housing
6 Protective Sleeve
7 Contact Holder
8 Contact Clip
9 PTFE Sleeve (Teflon)
10 PTFE Shaped Sleeve
Figure 6C1-1 – 35

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Engine Management – V6 – General Information Page 6C1-1–31

4.15 Ignition Coil and Spark Plug
Long-life platinum tip spark plugs are used which, along with
the ignition coil spark plug boot and spring, require
replacement at 100,000 kilometre service intervals. The
spark plugs, featuring a J-gap and a conical seat, do not
require inspection between services, and must not be re-
gapped.
Individual pencil-type ignition coils, one for each cylinder, are
mounted in the centre of the camshaft covers, and have
short boots connecting the coils directly to the spark plugs.
The pencil coil makes use of the space available in the spark
plug cavity in the cylinder head and camshaft cover. As a
pencil coil is always mounted directly on to the spark plug,
no high-tension ignition leads are required, further enhancing
reliability.

Figure 6C1-1 – 38
Pencil coils operate similarly to other compact coils, however
due to their shape, the structure differs considerably.
The central rod core (1) consists of laminations of varying
widths, stacked in packs that are nearly spherical. A yoke
plate (2), made from layered electrical sheet steel, provides
the magnetic circuit. The primary winding (3) is located
around the secondary winding (4), which supports the core.
A printed circuit board, or driver module, (5) is located at the
top of the coil and controls the firing of the coil based on
input from the ECM.
The ECM is responsible for maintaining correct spark timing
and dwell for all driving conditions. The ECM calculates the
optimum spark parameters from information received from
the various sensors, and triggers the appropriate ignition
module which then operates the coil.
The ignition coil / modules are supplied with the following
circuits:
• Ignition feed circuit.
• Ground circuit.
• Ignition control circuit.
• Reference low circuit.

Figure 6C1-1 – 39

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Engine Management – V6 – General Information Page 6C1-1–32

4.16 Intake Air Temperature Sensor
The intake air temperature (IAT) sensor is a thermistor,
which is a resistor that changes it’s resistance value based
on temperature.
The IAT sensor is part of the air mass sensor and is not a
serviceable item. The sensor is a negative temperature
coefficient (NTC) type, intake air temperature produces a
high sensor resistance while high engine coolant
temperature causes low sensor resistance.
Legend
A Temperature
B Resistance
The ECM provides a 5 V reference signal to the IAT and
monitors the return signal which enables it to calculate the
intake air temperature.
The ECM uses this signal to make corrections to the
operating parameters of the system based on changes in air
intake temperature.
Figure 6C1-1 – 40
4.17 Knock Sensor
The knock sensor (KS) signal is used by the ECM to provide
optimum ignition timing while minimising engine knock or
detonation.
The ECM monitors the voltage of the left-hand (Bank 2)
sensor during the 45 degrees after cylinder 2, 4, or 6 has
fired and the voltage of the right-hand (Bank 1) sensor
during the 45 degrees after cylinder 1, 3, or 5 has fired.
If knock occurs in any of the cylinders, the ignition will be
retarded by three degrees for that particular cylinder. If the
knocking then stops, the ignition will be restored to what it
was before in steps of 0.75 degrees.
Should knocking continue in the same cylinder despite of
the ignition being retarded, the ECM will retard the ignition
an additional step of three degrees, and so on, up to a
maximum of 12.75 degrees. The ignition will also be
retarded at high ambient temperatures to counteract
knocking tendencies provoked by high intake air
temperatures.
Should either Bank 1 or Bank 2 sensor fail to work, or
should an open circuit occur, the ignition timing will then be
set at a default strategy that will retard the ignition much
more than normal.
Figure 6C1-1 – 41

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Engine Management – V6 – General Information Page 6C1-1–35

5 Abbreviations and Glossary of
Te r m s
Abbreviations and terms used in this Section are listed below in alphabetical order with an explanation of the
abbreviation or term.
Abbreviation Description
A/C Air-conditioning
AC Alternating Current – An electrical current where the polarity is constantly changing between positive and
negative
A/F Air / Fuel (A/F Ratio)
Analogue Signal An electrical signal that constantly varies in voltage within a given parameter
Barometric Pressure Barometric absolute pressure (atmospheric pressure)
CAN Controller Area Network – A type of serial data for communication between electronic devices.
Catalytic Converter
A muffler-shaped device fitted in the exhaust system, usually close to the engine. Through chemical reaction,
a catalytic converter converts harmful gases produced by the combustion process such as HC, CO, and NOx,
into environmentally safe water vapour, carbon dioxide, and nitrogen.
CKT Circuit
Closed Loop A fuel control mode of operation that uses the signal from the exhaust oxygen sensor(s), to control the air / fuel
ratio precisely at a 14.7 to 1 ratio. This allows maximum efficiency of the catalytic converter.
CO Carbon Monoxide. One of the gases produced by the engine combustion process.
DC Direct Current
Digital Signal An electrical signal that is either on or off.
DLC
Data Link Connector. Used at the assembly plant to evaluate the engine management system. For service, it
allows the use of Tech 2 in performing system checks.
DLC Data Stream An output from the ECM initiated by Tech 2 and transmitted via the Data Link Connector(DLC).
DMM (10 M Ω) Digital Multimeter. A multipurpose meter that has capability of measuring voltage, current flow and resistance.
A digital multimeter has an input impedance of 10 M Ω (megohms), which means they draw very little power
from the device under test, they are very accurate and will not damage delicate electronic components
Driver An electronic device, usually a power transistor, that operates as an electrical switch.
DTC
Diagnostic Trouble Code. If a fault occurs in the engine management system, the ECM may set a four digit
diagnostic trouble code (DTC) which represents the fault condition. Tech 2 is used to interface with the ECM
and access the DTC(s). The ECM may also operate the malfunction indicator lamp in the instrument cluster.
Duty Cycle The time, in percentage, that a circuit is on versus off.
ECT Sensor
Engine Coolant Temperature sensor. A device that provides a variable voltage to the ECM based on the
temperature of the engine coolant.
EEPROM Electrically Erasable Programmable Read Only Memory. A type of read only memory (ROM) that can be
electrically programmed, erased and reprogrammed using Tech 2. Also referred to as Flash Memory
EMI or Electrical
Noise An unwanted signal interfering with a required signal. A common example is the effect of high voltage power
lines on an AM radio.
Engine Braking A condition where the engine is used to slow the vehicle on closed throttle or low gear.
EPROM Erasable Programmable Read Only Memory. A type of Read Only Memory (ROM) that can be erased with
ultraviolet light and then reprogrammed.
ESD Electrostatic Discharge. The discharge of static electricity which has built up on an insulated material
EVAP
Evaporative emission control system. Used to prevent fuel vapours from the fuel tank from entering into the
atmosphere. The vapours are stored in a canister that contains an activated charcoal element. The fuel
vapours are purged from the canister into the manifold to be burned in the engine.
GM LAN General Motors Local Area Network - A type of serial data for communication between electronic devices.
Fuse
A thin metal strip which melts when excessive current flows through it, creating an open circuit and protecting
a circuit from damage.
HC Hydrocarbon. Result of unburned fuel produced by incomplete combustion.
Heavy Throttle Approximately 3/4 of accelerator pedal travel (75% throttle position)
IAT Sensor
Intake Air Temperature sensor. A device that provides a variable voltage to the ECM based on the
temperature of air entering the intake system.
Ideal Mixture The air / fuel ratio which provides the best performance, while maintaining maximum conversion of exhaust
emissions, typically 14.7 to 1 on spark ignition engines
IGN Ignition
Inputs Information from sensors (MAF, TP, etc.) and switches (A/C request, etc.) used by the ECM to determine how
to control its outputs.

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Engine Management – V6 – General Information Page 6C1-1–36

Intermittent
An electrical signal that occurs now and then; not continuously. In electrical circuits, refers to occasional open,
short, or ground in a circuit
Light Throttle Approximately 1/4 of accelerator pedal travel (25% throttle position)
Low
A voltage less than a specific threshold. Operates the same as a ground and may, or may not, be connected
to chassis ground.
MAF Sensor Mass Air Flow Sensor. A device that provides a variable voltage to the ECM based on the amount of air flow
entering in the intake system.
Medium Throttle Approximately 1/2 of accelerator pedal travel (50% throttle position)
N.C Normally Closed. Switch contacts that are closed when they are in the normal operating position
N.O Normally Open. Switch contacts that are normally open when in the normal operating position
NOx
Nitrogen Oxide. One of the pollutants found in spark ignition engine exhaust that is formed from normal
combustion and increases in severity with combustion temperature.
O2 Sensor Oxygen Sensor. A device located in the exhaust system that provides a variable voltage to the ECM based on
the oxygen content of exhaust gas.
May also include a heating circuit to provide faster initial warm-up (HO2 sensor).
OBD On Board Diagnostic
Open Loop ECM control of the fuel control system without the use of the oxygen sensor signal.
Output Functions that are controlled by the ECM, typically these can include solenoids and relays, etc.
ECM Engine Control Module. An electronic device which controls the engine management system.
ECU Electronic Control Unit. An electronic device which controls specific system functions
PCV
Positive Crankcase Ventilation. Method of reburning crankcase fumes rather than passing them directly into
the atmosphere
PIM Powertrain Interface Module – The PIM acts as a communication translator between the ECM and other on-
board controllers that use a different serial data protocol.
PM Permanent Magnet
PWM
Pulse Width Modulated. A digital signal turned on and off for a percentage of available cycle time. A signal that
is 30% on and 70% of would be termed a 30% on PWM signal.
Quad Driver A transistor in the ECM capable of operating four separate outputs. Outputs can be either on-off or pulse width
modulated.
RAM Random Access Memory. A microprocessor can write into or read from this memory as needed. This memory
is volatile and needs a constant power supply to be retained. If the power is lost or removed, RAM data is lost.
r.p.m. Revolutions Per Minute
Serial Data
Serial data is a series of rapidly changing voltage signals pulsed from high to low. These signals are typically
transmitted through a wire often referred to as the Serial Data Circuit.
SFI Sequential Fuel Injection. Method of injecting fuel into the engine one cylinder at a time in relation to the
engines firing order.
Solenoid An electromagnetic coil which creates a magnetic field when current is applied, causing a plunger or ball to
move.
Switch Device to opens and close a circuit, thereby controlling current flow.
Tech 2
Tech 2 is a peripheral device that aids in the diagnosis and repair of electronic systems such as engine
management, transmission control etc. Tech 2 connects to the vehicle’s Data Link Connector (DLC).
TP Sensor Throttle Position sensor. A device that provides a variable voltage to the ECM based on the position of the
throttle plate.
Vacuum – manifold Vacuum sourced downstream of the throttle plate.
Vacuum – ported Vacuum sourced upstream of the throttle plate.
VSS Vehicle Speed Sensor. A permanent magnet type device that provides a digital voltage to the ECM.
WOT Wide Open Throttle – Full travel of the accelerator pedal (100% throttle position).


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Engine Management – V6 – Diagnostics Page 6C1-2–1

6C1-2 Engine Management – V6
Diagnostics
ATTENTION
Before performing any service operation or other procedure described in this Section, refer to 1.5 Warning
Caution and Notes for correct workshop practices with regard to safety and/or property damage.
1 General Information ............................................................................................................ ...................4
1.1 Diagnostic System Check ..................................................................................................................................... 4
1.2 Diagnostic Trouble Code Tables ................................................................................................. ......................... 4
1.3 Symptoms Diagnostics ......................................................................................................................................... 5
1.4 Diagnostic Trouble Codes .................................................................................................................................... 5
1.5 Warning Caution and Notes .................................................................................................................................. 6
2 GM LAN Serial Communication Circuit ............................................................................................ ....8
3 Wiring Diagrams and Connector Charts ........................................................................................... ...9
3.1 Wiring Diagrams .................................................................................................................................................... 9
3.2 ECM Connector End Views ................................................................................................................................. 12
3.2 Engine Control Connector End Views ............................................................................................. .................. 16
4 Diagnostics Starting Point...................................................................................................................18
4.1 Basic Requirements ............................................................................................................................................ 18
4.2 Diagnostic Precautions ......................................................................................................... .............................. 18
4.3 Preliminary Checks.............................................................................................................................................. 19
4.4 Diagnostic System Check ........................................................................................................ ........................... 20
5 Symptoms Diagnostics ........................................................................................................................22
5.1 Symptoms Diagnosis Table ....................................................................................................... ......................... 22
5.2 Intermittent Fault Conditions .............................................................................................................................. 22
5.3 Backfire................................................................................................................................................................. 24
5.4 Cranks But Does Not Run ........................................................................................................ ........................... 26
5.5 Cuts Out, Misses.................................................................................................................................................. 27
5.6 Detonation / Spark Knock ....................................................................................................... ............................ 28
5.7 Dieseling, Run-on ................................................................................................................................................ 28
5.8 Hard Start ............................................................................................................................................................. 29
5.9 Hesitation, Sag and Stumble .................................................................................................... .......................... 30
5.10 Lack of Power, Sluggishness or Sponginess ...................................................................................... ............. 31
5.11 Poor Fuel Economy ............................................................................................................................................. 32
5.12 Rough, Unstable, Incorrect Idle or Stalling .................................................................................... ................... 34
5.13 Surges / Chuggles ............................................................................................................................................... 35
6 Functional Checks................................................................................................................................37
6.1 General Information ............................................................................................................ ................................. 37
6.2 Fuel Injector Coil Test ......................................................................................................................................... 37
6.3 Fuel Injector Balance Test ..................................................................................................... ............................. 42
6.4 Fuel Injector Leak Down Test ................................................................................................... .......................... 44
6.5 Alcohol / Contaminants in Fuel Diagnosis ....................................................................................... ................. 46
6.6 Crankshaft Position (CKP) System Variation Learn Procedure..................................................................... .. 46
6.7 Throttle Body Relearn.......................................................................................................................................... 47

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Engine Management – V6 – Diagnostics Page 6C1-2–4

1 General Information
1.1 Diagnostic System Check
The engine management diagnostic procedure is organised in a logical structure that begins with the Diagnostic System
Check. The Diagnostic System Check directs the diagnostic procedure to the logical steps necessary to diagnose an
engine driveability fault condition.
1.2 Diagnostic Trouble Code Tables
The Diagnostic System Check directs the diagnostic procedure to the appropriate diagnostic trouble code (DTC) tables
if there is a DTC currently stored in the engine control module (ECM).
The diagnostic tables locate a faulty circuit or component through a logic based on the process of elimination. These
diagnostic tables are developed with the following assumptions:
• the vehicle functioned correctly at the time of assembly,
• there are no multiple faults, and
• the problem currently exists.
Understanding and the correct use of the diagnostic tables are essential to reduce diagnostic time and to prevent
misdiagnosis.
Multiple DTC Fault Conditions
Some fault conditions trigger multiple component DTCs even if the fault condition exists only on a single component. If
there are multiple DTCs stored in the ECM, the service technician must view and record all DTCs logged.
The relationship between the logged DTCs can then be analysed to determine the source of the fault condition. Always
begin the diagnostic process with the DTC table of the fault condition that may trigger other DTCs to set.
The following fault conditions may trigger multiple DTCs:
• a fault in the serial data communication circuit,
• a system voltage that is too low may cause incorrect engine management system operation or engine
management component malfunction,
• a system voltage that is too high may damage the ECM and/or other engine management components,
• fault condition in the ECM read only memory (ROM) or random access memory (RAM),
• fault condition in the ECM internal circuitry or programming,
• improperly connected sensor or component wiring connector, or
• an electrical fault condition in the following shared ECM electrical circuits trigger DTCs on components or sensors
that share in the faulty shared circuit. Test the electrical circuit of the appropriate sensors or components to isolate
the fault condition. Refer to 3 W iring Diagrams and Connector Charts in this Section.
• 5 V Reference Circuit,
• Low Reference Circuit, or
• Ignition Control Voltage Circuit.
If there are no obvious faults to begin a multiple DTC fault condition diagnostic procedure, diagnose the DTCs in the
following order unless directed otherwise:
1 Always start with the lowest numbered component level DTCs such as:
• sensor DTCs,
• solenoid DTCs, or
• relay DTCs.
2 Then follow with system level DTCs such as:
• misfire DTCs,

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Engine Management – V6 – Diagnostics Page 6C1-2–8

2 GM LAN Serial Communication
Circuit

Figure 6C1-2 – 1

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