2007 ISUZU KB P190 switches

Engine Management – V6 – General Information Page 6C1-1–14

Throttle Body Relearn Procedure
The ECM stores values that include the lowest possible TP sensor positions (zero percent), the rest positions (seven
percent), and the spring return rate. These values will only be erased or overwritten if the ECM is reprogrammed or if a
throttle body relearn procedure is performed.
NOTE
If the battery has been disconnected, the ECM
performs a throttle body relearn procedure once
the battery has been reconnected and the ignition
turned on.
The ECM performs a throttle body relearn procedure anytime the ignition is turned on and the following conditions have
been met:
• The engine has been off for greater than 29 seconds,
• The engine speed is less than 40 rpm,
• The vehicle speed is 0 km/h,
• The engine coolant temperature (ECT) is 5 – 60°C; if Tech 2 is used to perform the relearn procedure, the ECT is
5 – 100°C,
• The intake air temperature (IAT) is greater than 5 – 60°C; if Tech 2 is used to perform the relearn procedure, the
IAT is 5 – 100°C,
• The APP sensor angle is less than 15 percent, and
• Ignition voltage is greater than 10 V.
The throttle body relearn procedure is performed 29 seconds after the ignition is turned on. The ECM commands the
throttle plate from the rest position (seven percent open) to full closed (zero percent), then to around 10 percent open.
This procedure takes about six – eight seconds. If any faults occur in the TAC system, a DTC sets. At the start of this
procedure, the Tech 2 TAC Learn Counter parameter should display 0, then count up to 11 after the procedure is
completed. If the counter did not start at 0, or if the counter did not end at 11, a fault has occurred and a DTC should set.
TAC System Default Actions / Reduce Power Modes
The ECM switches to the following reduce power modes if the ECM detects a fault condition in the TAC system:
• If an APP sensor circuit fault or TP sensor circuit fault is detected, the ECM limits engine torque so the vehicle
cannot reach speeds of greater than 100 km/h. The ECM remains in this reduce power mode during the entire
ignition cycle, even if the fault is corrected.
• If there is a fault condition with the throttle actuator control circuits, a throttle actuator command vs. actual position
fault, a return spring check fault, or a TP sensor one circuit fault, the ECM limits engine speed to 2500 rpm and
three – six fuel injectors are randomly disabled. At this time the reduce power indicator is commanded on. The
ECM remains in the reduce power mode during the entire ignition cycle even if the fault is corrected.
NOTE
If a TP sensor one or throttle actuator control
circuit fault is present at the time the vehicle is at
idle, with no accelerator pedal angle, the engine
may stall.
Forced Engine Shutdown
A further safety feature which is built into the TAC system is the ECM will initiate an engine shut down if, the ECM’s
internal monitoring functions detects a serious internal fault, the fuel injectors will be turned off.
3.6 Cruise Control System
The cruise control system integrates with the engine control module (ECM) through the powertrain interface module
(PIM), to control the electronic throttle actuator and maintain the vehicle at the speed set by the driver.

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Engine Management – V6 – General Information Page 6C1-1–15

W hen the cruise control ON-OFF switch, located on the right hand side of the dash panel, is pressed, the PIM, on
receiving the input from the switch, turns on the cruise ON-OFF switch warning lamp to inform the user that the cruise
control has been engaged.
W hen the cruise control switch assembly is pressed to SET/COAST, the PIM on receiving the input, sends a signal via
the serial data bus to the ECM. Providing the pre-conditions for cruise control operation have been met, the ECM
activates cruise control and commands the PIM to turn on the instrument cluster cruise set warning lamp, to inform the
user that cruise control is active. The ECM receives all the various inputs required to maintain the correct speed and then
controls the throttle plate depending on the load on the engine (ascending or descending hills, etc).
The cruise control is deactivated by either pressing the brake pedal, clutch pedal, cruise CANCEL or by the cruise control
ON-OFF button. In each of these instances, the ECM receives an input when any of these switches are activated. For
further information on the cruise control system, refer to 8C Cruise Control – HFV6.
3.7 Brake Torque Management
Brake torque management places limits on engine torque when the brakes are applied, regardless of the accelerator
pedal position (APP). The conditions under which brake torque management occur are as follows:
• The accelerator has been depressed before the brakes are applied,
• The brakes are applied and the ECM receives an input from the stop lamp switch,
• Vehicle speed is greater than 5 km/h,
• Engine speed is greater than 1200 rpm and
• Conditions exist for greater than 2.5 seconds.
W hen brake torque management has been implemented, the torque is reduced by altering the throttle plate opening by
25%. The ECM will monitor the rate at which the vehicle is slowing and adjust the throttle plate opening accordingly.
3.8 Emission Control Systems
Evaporative Emission Control System
The evaporative emission control system used is the
activated carbon (charcoal) canister storage method. Fuel
vapour is drawn from the fuel tank into the canister where it
is held by the activated carbon until the ECM commands the
evaporative emission (EVAP) purge solenoid valve to open.
The ECM energises the EVAP purge solenoid valve by
applying a pulse width modulated (PW M) ground to the
EVAP purge solenoid valve control circuit.
Figure 6C1-1 – 9

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Engine Management – V6 – General Information Page 6C1-1–22

4.6 Clutch Pedal Switch Assembly – Manual
Vehicles Only
The cruise control cancel switch (1) is normally closed when
the clutch pedal is at rest, opening when the pedal is
pressed. Activation of this switch removes the signal to the
ECM which will then deactivate the cruise control. For
further information on the cruise control system, refer to
7A1 Clutch – V6.
Figure 6C1-1 – 19
4.7 Engine Control Module
Located at the right front of the engine assembly, the engine
control module (ECM) monitors input signals from the
various sensors and switches connected to the engine
management system. The ECM processes this information,
to control the following:
• fuel delivery and injection system,
• throttle actuation system,
• ignition system,
• on-board diagnostics,
• the engine cooling fan, and
• the air-conditioner compressor clutch (where fitted).
The ECM supplies 5 V to the various sensors through pull-
up resistors to the internal regulated power supplies.
The ECM controls output circuits such as the injectors, etc.
by applying control signal to the ground circuits of the
components through transistors or a device inside the ECM
called a driver. The exception to this is the fuel pump relay
control circuit. The fuel pump relay is the only ECM
controlled circuit where the ECM controls the 12 V sent to
the coil of the relay. The ground side of the fuel pump relay
coil is connected to engine ground.
The ECM communicates directly with the various control
units within the vehicle using the General Motors local area
network (GM LAN) serial data communication protocol.
Refer to 3.9 Serial Data Communication System.
Figure 6C1-1 – 20

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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 – Diagnostics Page 6C1-2–133

Step Action Yes No
13 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.
7.28 DTC P0504 or P0571
DTC Descriptor
This diagnostic procedure supports:
• DTC P0504 – Brake Switch Circuit Malfunction.
• DTC P0571 – Cruise Control Brake Switch Circuit
Circuit Description
The brake switch assembly is comprised of two individual switches, a stop lamp switch and cruise control cancel switch.
The ECM uses inputs from both of these switches for enabling cruise control, brake torque management etc. For further
information on the brake switch assemblies, refer to 6C1–1 Engine Management – V6 – General Information.
The ECM monitors both switches, and if the signals do not correlate, DTC P0504 will set. If the ECM determines that a
fault exists in the cruise control cancel circuit, DTC0571 will set.
Conditions for Running the DTC
Run continuously once the following conditions are met:
• The ignition is switched on.
• The ignition voltage is 10.0 – 16.0 V.
Conditions for Setting the DTC
The ECM detects one of the following conditions:
• Only one switch signal is present when the vehicle accelerates or decelerates rapidly ten times.
NOTE
The ECM will count over several drive cycles.
• A signal is seen from the stop lamp switch and cruise control cancel switch when the vehicle accelerates rapidly.
• The ECM does not detect a signal from the switches during braking.
Conditions for Clearing the DTC
The brake switch circuit DTC is a Type B DTC. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action
taken when Type B DTCs set and conditions for clearing Type C DTCs.
Additional Information
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the brake switch operation.
• Refer to 8C Cruise Control – HFV6 for brake pedal switch operation and testing.
• Since a 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.

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Engine Management – V6 – Diagnostics Page 6C1-2–134

Test Description
The following number refers to the step numbers in the diagnostic table:
3 A fault condition in the stop lamp switch assembly may trigger these DTCs.
DTC P0504 or P0571 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 P0504 or DTC P0571 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 1 Ignition ON, engine OFF.
2 On Tech 2 select: Engine / V6 Engine / Data Display / Cruise
Control Data .
3 Observe the status of the brake lamp switch and cruise control cancel switch.
4 Fully depress the brake pedal.
Does Tech 2 display change from Inactive to Active in all switches
when the pedal is pressed? Refer to Additional
Information in this DTC Go to Step 4
4 Did the brake lamp switch Tech 2 status fail to change?
Go to Step 5 Go to Step 9
5 1 Disconnect the wiring connector from the brake switch
assembly. Refer to 8C Cruise Control.
2 Ignition ON.
3 Connect a test lamp between the voltage circuit of the stop lamp switch and a good ground.
Does the test lamp illuminate? Go to Step 7 Go to Step 6
6 1 Repair the high resistance or open circuit fault condition in the
voltage circuit of the stop lamp switch. Refer to 8A Electrical -
Body and Chassis for information on electrical wiring repair
procedures.
W as the repair completed? Go to Step 14 —
7 1 Test the stop lamp switch. Refer to 8C Cruise Control – HFV6.
W as any fault found and rectified? Go to Step 14 Go to Step 8
8 1 Test the control circuit of the stop lamp switch for a high
resistance, open circuit, short to ground or short to voltage fault
condition. Refer to 8A Electrical - Body and Chassis for
information on electrical fault diagnosis.
W as the repair completed? Go to Step 14 Go to Step 13
9 1 Disconnect the wiring connectors from the brake switch
assembly. Refer to 8C Cruise Control – HFV6.
2 Ignition ON.
3 Connect a test lamp between the voltage circuit of the cruise control cancel switch and a good ground.
Does the test lamp illuminate? Go to Step 11 Go to Step 10

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Engine Management – V6 – Diagnostics Page 6C1-2–159

Conditions for Running the DTC
DTCs P0685, P0686 and P0687 run continuously once the following conditions are met:
• The ignition is switched on
• The ignition voltage is 10.0 – 16.0 V.
Conditions for Setting the DTC
The ECM detects a condition that is incorrect for the engine control relay commanded state.
Conditions for Clearing the DTC
The engine control relay control circuit DTCs are Type C DTCs. Refer to 1.4 Diagnostic Trouble Codes in this
Section, for action taken when Type C DTCs set and conditions for clearing Type C DTCs.
Additional Information
• 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 number refers to the step number in the diagnostic table:
4 Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.
DTC P0685, P0686 or P0687 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 Turn the ignition switch to the Start position or operate the vehicle within the conditions for running the DTC.
3 Using Tech 2, select the DTC display function.
Does DTC P0685, P0686 and P0687 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 1 Remove the engine control relay. Refer to 8A Electrical - Body
and Chassis.
2 Connect a test lamp between the battery voltage circuit of the engine control relay and a good ground.
Does the test lamp illuminate? Go to Step 4 Go to Step 5
4 1 Switch off the ignition.
2 Remove and reinstall the ECM fuse 29 from the engine compartment fuse and relay panel assembly.
3 Connect a test lamp between the control circuit and the battery voltage circuit of the engine control relay.
4 Switch on the ignition.
Does the test lamp switches from off to on when the ignition switch is
turned form off to on? Go to Step 7 Go to Step 6

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Engine Management – V6 – Diagnostics Page 6C1-2–209

The low voltage output is 0 – 450 mV, which occurs if the air fuel mixture is lean.
The high voltage output is 450 – 1,000 mV, which occurs if the air fuel mixture is rich.
The ECM monitors, stores and evaluates the HO2S 2 voltage fluctuation information to determine the level of oxygen
concentration in the exhaust.
Conditions for Running the DTC
DTC P2231 or P2234
Run continuously once the following conditions are met:
• DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0053, P0059, P0130, P0135, P0150 or P0155 are not set.
• The HO2S heater control is enabled.
• The HO2S heater duty cycle is greater than 5 percent.
• The HO2S is at operating temperature for 10 seconds.
• The ECM does not detect an engine misfire fault condition.
• The fuel injectors are enabled.
• The ignition voltage is 10.5 – 18 V.
• The calculated exhaust temperature is less than 800 °C.
• The MAF sensor signal output is steady within 3 percent of the airflow into the engine.
DTC P2232 and P2235
Run continuously once the following conditions are met:
• The engine is running.
• The HO2S is at operating temperature for longer than 90 seconds.
• The fuel injectors are enabled.
• The ignition voltage is greater than 10.5 V.
• The calculated exhaust temperature is 250 – 800 °C.
DTC P2251 and P2254
Run continuously once the following conditions are met:
• DTCs P0030, P0031, P0032, P0050, P0051 and P0052 ran and passed.
• The HO2S heater control is enabled.
• The ECM internal sensing element resistance is greater than 570 Ω.
• The ECM detects the internal HO2S signal voltage is 1.47 – 1.53 V.
• The HO2S is at operating temperature.
Conditions for Setting the DTC
DTC P2231 or P2234
The ECM detects the following conditions:
• The internal HO2S signal voltage changes greater than 100 mV as the heater control switches.
• The above condition occurs 18 times in the last 10 seconds.
DTC P2232 or P2235
The ECM detects the following conditions:

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