2007 ISUZU KB P190 heating

Engine Management – V6 – Diagnostics Page 6C1-2–82

• DTC P0131 – O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
• DTC P0132 – O2 Sensor Circuit High Voltage (Bank 1, Sensor 1)
• DTC P0133 –
• DTC P0135 – O2 Sensor Heater Circuit Range / Performance (Bank 1, Sensor 1)
• DTC P0137 – O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
• DTC P0138 – O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
• DTC P0140 – O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2)
• DTC P0141 – O2 Sensor Heater Circuit Range / Performance (Bank 1, Sensor 2)
• DTC P0150 – O2 Sensor Circuit Malfunction (Bank 2, Sensor 1)
• DTC P0151 – O2 Sensor Circuit Low Voltage (Bank 2, Sensor 1)
• DTC P0152 – O2 Sensor Circuit High Voltage (Bank 2, Sensor 1)
• DTC P0155 –O2 Sensor Heater Circuit Range / Performance (Bank 2, Sensor 1)
• DTC P0157 – O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)
• DTC P0158 – O2 Sensor Circuit High Voltage (Bank 2, Sensor 2)
• DTC P0160 – O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2)
• DTC P0161 – O2 Sensor Heater Circuit Range / Performance (Bank 2, Sensor 2)
• DTC P2243 – O2 Sensor Voltage Signal Circuit Malfunction (Bank 1, Sensor 1)
• DTC P2247 – O2 Sensor Voltage Signal Circuit Malfunction (Bank 2, Sensor 1)
• DTC P2270 – O2 Sensor Lean / Rich Switch Signal Malfunction (Bank 1, Sensor 2)
• DTC P2271 – O2 Sensor Rich / Lean Switch Signal Malfunction (Bank 1, Sensor 2)
• DTC P2272 – O2 Sensor Lean / Rich Switch Signal Malfunction (Bank 2, Sensor 2)
• DTC P2273 – O2 Sensor Rich / Lean Switch Signal Malfunction (Bank 2, Sensor 2)
• DTC P2297 – O2 Sensor Range / Performance During Deceleration Fuel Cutoff (Bank 1, Sensor 1)
• DTC P2298 – O2 Sensor Range / Performance During Deceleration Fuel Cutoff (Bank 2, Sensor 1)
Circuit Description
The engine control relay applies positive voltage to the heater ignition voltage circuits of the HO2S. The ECM applies a
pulse width modulated (PW M) ground to the heater control circuit of the HO2S through a device within the ECM called a
driver, to control the HO2S rate of heating.
HO2 Sensor 2
The ECM applies a voltage of approximately 450 mV between the reference signal circuit and low reference circuit of the
HO2S while the sensor temperature is less than the operating range.
Once the HO2S reaches operating temperature, the sensor varies this reference signal voltage, which constantly
fluctuates between the high voltage output and the low voltage output.
• 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 voltage fluctuation information to determine the level of oxygen
concentration in the exhaust.
HO2 Sensor 1
The ECM maintains the voltage between the reference signal circuit and low reference circuit of the HO2S 1 to about
450 mV by increasing or decreasing the oxygen content in the HO2S diffusion gap. To achieve this, the ECM controls
the current applied to the oxygen pumping cell in the HO2S

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ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–208

Step Action Yes
No
11 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 BARO pressure sensor circuit DTCs fail this ignition
cycle? Go to Step 2 Go to Step 12
12 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.
7.58 DTC P2231, P2232, P2234, P2235, P2251
or P2254
DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC P2231 – O2 Sensor Signal Interference by Heater Circuit (Bank 1, Sensor 1)
• DTC P2232 – O2 Sensor Signal Short to Heater Circuit (Bank 1, Sensor 2)
• DTC P2234 – O2 Sensor Signal Interference by Heater Circuit (Bank 2, Sensor 1)
• DTC P2235 – O2 Sensor Signal Short to Heater Circuit (Bank 2, Sensor 2)
• DTC P2251 – O2 Sensor Ground Circuit Malfunction (Bank 1, Sensor 1)
• DTC P2254 – O2 Sensor Ground Circuit Malfunction (Bank 2, Sensor 1)
Circuit Description
The Engine control relay applies positive voltage to the heater ignition voltage circuits of the HO2S. The ECM applies a
pulse width modulated (PW M) ground to the heater control circuit of the HO2S through a device within the ECM called a
driver, to control the HO2S rate of heating.
O2 Sensor 1
The ECM maintains the voltage between the reference signal circuit and low reference circuit of the HO2S 1 to about
450 mV by increasing or decreasing the oxygen content in the HO2S diffusion gap. To achieve this, the ECM controls
the current applied to the oxygen pumping cell in the HO2S.
• If the air / fuel mixture in the exhaust is balanced (lambda = 1), the oxygen pumping cell current is zero.
• If the exhaust gas in the HO2S 1 diffusion gap is lean, the ECM applies a positive current to the oxygen pumping
cell to discharge oxygen from the diffusion gap.
• If the exhaust gas in the HO2S 1 diffusion gap is rich, the ECM applies a negative current to the oxygen pumping
cell to draw oxygen into the diffusion gap.
The pumping current required to maintain the HO2S 1 signal circuit voltage to about 450 mV is proportional to the level
of oxygen concentration in the exhaust gas. The ECM monitors and evaluates the oxygen pumping current to determine
the level of oxygen concentration in the exhaust.
An HO2S signal circuit shorted to heater control circuit DTC sets if the ECM detects the HO2S signal voltage is
increasing or decreasing at the same rate as the HO2S heater control circuit.
O2 Sensor 2
The ECM applies a voltage of approximately 450 mV between the reference signal circuit and low reference circuit of the
HO2S 2 while the sensor temperature is less than the operating range.
Once the HO2S 2 reaches operating temperature, the sensor varies this reference signal voltage, which constantly
fluctuates between the high voltage output and the low voltage output.

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ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–211

Step Action Yes No
4 1 Disconnect the ECM and the appropriate HO2S connector.
2 From the HO2S wiring connector to the ECM wiring connector, test the following circuit for a shorted to the sensor heater
control circuit fault condition:
• Reference signal circuit,
• low reference circuit,
• pump current,
• input pump current.
Refer to 8A Electrical - Body and Chassis for information on electrical fault diagnosis.
W as any fault found and rectified? Go to Step 8 Go to Step 7
6 Replace the appropriate HO2S. Refer to 6C1-3 Engine Management
– V6 – Service Operations.
W as the repair completed? Go to Step 8 —
7 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 8 —
8 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 O2 Sensor Signal Circuit Shorted to Heater Control
Circuit DTCs fail this ignition cycle? Go to Step 2 Go to Step 9
9 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.
7.59 DTC P2237, P2238, P2239, P2240, P2241
or P2242
DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC P2237 – O2 Sensor Pump Current Circuit Malfunction (Bank 1, Sensor 1)
• DTC P2238 – O2 Sensor Pump Current Circuit Low Voltage (Bank 1, Sensor 1)
• DTC P2239 – O2 Sensor Pump Current Circuit High Voltage (Bank 1, Sensor 1)
• DTC P2240 – O2 Sensor Pump Current Circuit Malfunction (Bank 2, Sensor 1)
• DTC P2241 – O2 Sensor Pump Current Circuit Low Voltage (Bank 2, Sensor 1)
• DTC P2242 – O2 Sensor Pump Current Circuit High Voltage (Bank 2, Sensor 1)
Circuit Description
The engine control relay applies positive voltage to the heater ignition voltage circuits of the HO2S #1. The ECM applies
a pulse width modulated (PW M) ground to the heater control circuit of the HO2S through a device within the ECM called
a Driver, to control the HO2S rate of heating.
The ECM maintains the voltage between the reference signal circuit and low reference circuit of the HO2S #1 to about
450 mV by increasing or decreasing the oxygen content in the HO2S diffusion gap. To achieve this, the ECM controls
the current applied to the oxygen pumping cell in the HO2S.

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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 – Service Operations Page 6C1-3–17


Clean the area around the ECT before
removal to avoid debris from entering the
engine.
5 Remove the ECT sensor (1). NOTE
If coolant leaks from the cylinder head as the
sensor is removed, screw the sensor back into
the cylinder head and drain more coolant from
the cooling system.
6 If required, test the ECT sensor, refer to the Test in this Section.
Figure 6C1-3 – 13
Test

To prevent component damage, use
connector test adaptor kit J 35616-A.
Resistance Check
1 Suspend the engine coolant temperature (ECT) sensor and a suitable thermometer in a container of 50/50 DEX- COOL® long life coolant or equivalent and water.
NOTE
Neither the ECT sensor or thermometer should
rest on the bottom of the container due to an
uneven concentration of heat at this point when
the container is heated.
2 Connect a digital ohmmeter using connector test adaptor kit J 35616-A to the ECT sensor.
3 Measure the resistance across terminals 1 and 2.
4 W hilst heating the container, observe the resistance values as the temperature increases and compare the
temperature / resistance change to the specifications.

Figure 6C1-3 – 14

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ISUZU KB P190 2007

Engine Management – V6 – Service Operations Page 6C1-3–50

• plug/s overheating due to insufficient tightening (caused by combustion gases leaking past the threads).
Broken Insulator
Broken insulators are usually the result of improper installation or carelessness.
Breaks in the upper insulator can result from a poor fitting spark plug socket or impact. The cracked insulator may not
show up until oil or moisture penetrates the crack. The crack is often just below the crimped part of the shell and may not
be visible.
Breaks in the lower insulator often result from careless re-gapping and are usually visible.
This can also result from the plug operating too hot. For example, in periods of high speed operation or under heavy
loads.

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Engine Management – V6 – Service Operations Page 6C1-3–52

Oil Fouled (3)
W et, oily deposits with minor electrode wear possibly due to oil leaking past worn piston rings.
Breaking in a new or recently overhauled engine before the rings are fully seated may also result in this condition.
Deposit Fouling A (4)
Red brown, yellow and white coloured coatings on the insulator tip which are by-products of combustion. They come
from fuel and lubricating oil which generally contain additives. Most powdery deposits have no adverse effect on spark
plug operation, however, they may cause intermittent missing under severe operating conditions.
Deposit Fouling B (5)
Deposits similar to those identified in deposit fouling A (4). These are also by-products of combustion from fuel and
lubricating oil. Excessive valve stem clearances and / or defective intake valve seals allow too much oil to enter the
combustion chamber. The deposits will accumulate on the portion of the spark plug that projects into the chamber and
will be heaviest on the side facing the intake valve. If this condition is only detected in one or two cylinders, check the
valve stem seals.
Deposit Fouling C (6)
Most powdery deposits identified in deposit fouling A (4) have no adverse effect on the operation of the spark plug as
long as they remain powdery.
Under certain conditions of operation however, these deposits melt and form a shiny glaze coating on the insulator.
W hen hot, this acts as a good electrical conductor allowing the current to flow along the deposit instead of sparking
across the gap.
Detonation (7)
Commonly referred to as engine knock or pinging, detonation causes severe shocks inside the combustion chamber
causing damage to parts.
Pre-ignition (8)
Burnt or blistered insulator tip and badly eroded electrodes probably due to the excessive heat.
This is often caused by a cooling system blockage, sticking valves, improperly installed spark plugs or plugs that are the
wrong heat rating (too hot).
Sustained high speed with a heavy load can produce temperatures high enough to cause pre-ignition.
Heat Shock Failure (9)
A rapid increase in spark plug tip temperature under severe operating conditions can cause heat shock and result in
fractured insulators. This is a common cause of broken and cracked insulator tips.
Insufficient Installation Torque (10)
Poor contact between the spark plug and the cylinder head seat.
The lack of proper heat transfer that results from poor seat contact causes overheating of the spark plug. In many cases,
severe damage occurs. Dirty threads in the cylinder head can cause the plug to seize before it is seated.
Ensure the cylinder head and spark plug threads are free of deposits, burrs and scale before installation.

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ISUZU KB P190 2007

Charging System – V6 Page 6D1-1-12


7 Reconnect the battery ground cable P-5.
8 Fit a loading device (7) across the battery terminals, e.g. an adjustable carbon pile.

The loading device must have a minimum
power consumption of 1000 W.
9 Record the voltage reading before starting the engine. (This reading should increase when the engine is running, indicating generator output.).
10 Start the engine.
11 Increase the engine speed to the value outlined in the chart below.
12 Using the reading from the multimeter set to measure current, adjust the loading device to apply a load within the range outlined in the chart below.
13 Using the multimeter set to measure voltage, check the generator output voltage against the specification.
Engine RPM ........................................................... 1300
Load ................................................................ 5.0 – 10 A
Output Voltage ........................................... 13.8 – 15.4 V

Load Regulation Test
NOTE
The decrease in the voltage recorded during this
test should not exceed 0.5 V from the readings
obtained for the Regulating Voltage Test. If the
decrease in the regulating voltage is greater than
0.5 V, the regulator is defective. Replace the
regulator.
14 Increase the engine speed to the value outlined in the chart below.
15 Using the reading from the multimeter set to measure current, adjust the loading device to apply a load of about 90% of the generator’s full output.
16 Using the multimeter set to measure voltage, check the generator output voltage against the specification.
Engine RPM............................................................ 1900
Load ......................................................................... 90 A
Output Voltage ........................................... 13.8 – 15.4 V
Full Load Output Test

Keep the time for this test to a minimum to
avoid undue heating and high engine speeds.
17 Increase the engine speed to the value outlined in the chart below .
18 Using the reading from the multimeter set to measure voltage, adjust the loading device to increase the load until the generator output voltage drops to 13.5 V. Full generator output, outlined in the chart below, is required.
19 Record the current reading displayed on the multimeter set to measure current.

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