2007 ISUZU KB P190 CIRCUIT DIAGRAM

Engine Management – V6 – Diagnostics Page 6C1-2–70

Additional Information
• The MAF sensor circuit DTCs is a 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 DTC.
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the MAF sensor operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Inspect the MAF sensor for an incorrectly routed harness or if the harness is too close to the following:
− ignition coil,
− solenoids,
− relays, and
− motors.
• A low minimum air rate may cause this DTC to set during deceleration. Inspect for the following conditions:
− a plugged or a collapsed intake air duct, or a dirty air filter element,
− objects that block the MAF sensor air inlet screen, and
− sticking or dirty throttle plate or throttle bore.
• Any un-metered air that enters the engine may cause this DTC to set. Inspect for vacuum leaks in the following:
− intake manifold,
− throttle body,
− barometric pressure (BARO) sensor seal,
− EVAP canister purge valve seal,
− brake booster system,
− air induction system, and
− crankcase ventilation system.
• 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.
DTC P0101, P0102 or P0103 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 P0101, P0102 or P0103 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC

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Engine Management – V6 – Diagnostics Page 6C1-2–73

• Increased temperature in the intake air decreases the resistance value of the IAT sensor. This increases the IAT
sensor pull-down rate to ground. Therefore, the higher the intake air temperature, the lower the signal voltage
output of the IAT sensor.
• Decreased temperature in the intake air increases the resistance value of the IAT sensor. This reduces the IAT
sensor pull-down rate to ground. Therefore, the lower the intake air temperature, the higher the signal voltage
output of the IAT sensor.
An IAT sensor circuit DTC sets if the ECM detects the intake air temperature is outside the specified range.
Conditions for Running the DTC
Runs continuously once the following conditions are met:
• The engine is running for longer than 3.0 minutes.
• The engine is idling for longer than 10.0 seconds
Conditions for Setting the DTC
DTC P0112
The ECM detects the intake air temperature is greater than 132 °C for longer than 3.0 seconds.
DTC P0113
The ECM detects the intake air temperature is less than - 38 °C for longer than 3.0 seconds.
Conditions for Clearing the DTC
The IAT sensor DTCs are Type B DTCs. 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 DTC.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the IAT Sensor operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Test the IAT sensor using the IAT Temperature vs. Resistance in 6C1-3 Engine Management – V6 – Service
Operations. If the engine has sat overnight, the IAT sensor should display within 3 °C of the ECT sensor values.
• 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:
3 Tests the signal circuit of the IAT sensor.
4 Measures the integrity of the IAT sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.
DTC P0112 or P0113 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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Engine Management – V6 – Diagnostics Page 6C1-2–74

Step Action Yes No
2 1 Switch off the ignition for 30 seconds.
2 Start the engine.
3 Allow the engine to reach the normal operating temperature.
4 Using Tech 2, select the DTC display function.
Does DTC P0112 or P0113 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 1 Switch off the ignition.
2 Disconnect the IAT sensor wiring connector.
3 Switch on the ignition with the engine not running.
4 Using a digital multimeter, measure the voltage between the IAT sensor signal circuit and the ECM housing.
Does the multimeter display 4.8 – 5.2 V? Go to Step 4 Go to Step 5
4 1 Switch off the ignition.
2 Remove ECM Fuse 29 from the engine compartment fuse and relay panel assembly.
3 Using a digital multimeter, measure the resistance between the IAT 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 7 Go to Step 6
5 Test the IAT sensor signal circuit 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 any fault found and rectified? Go to Step 9 Go to Step 8
6 Test the IAT sensor low reference circuit 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.
NOTE
The IAT sensor shares the low reference circuit with other
sensors. A fault condition in the low reference circuit may
trigger DTCs on sensors that share this circuit. Refer to
3 W iring Diagrams and Connector Charts in this Section,
to assist diagnosis.
W as any fault found and rectified? Go to Step 9 Go to Step 8
7 Replace the IAT sensor. Refer to 6C1-3 Engine Management – V6 –
Service Operations
W as the repair completed? Go to Step 9 —
8 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations
W as the repair completed? Go to Step 9 —

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Engine Management – V6 – Diagnostics Page 6C1-2–76

Conditions for Setting the DTC
DTC P0116
The ECM detects the engine coolant temperature sensor value is 10°C less than the minimum calculated engine
temperature.
DTC P0117
The ECM detects the engine coolant temperature is greater than 140 °C for longer than 3 seconds.
DTC P0118
The ECM detects the engine coolant temperature is less than -39 °C for longer than 3 seconds.
DTC P0125
The ECM determines the calculated engine temperature by measuring the amount of airflow into the engine. This DTC
sets if the ECM detects the actual ECT sensor is not within 10ºC of the calculated engine temperature for approximately
2 – 5 minutes.
DTC P1258
The ECM detects the engine coolant temperature is greater than 131 °C for longer than 2 seconds.
Conditions for Clearing the DTC
The ECT sensor DTCs are Type B DTCs. 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 DTC.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the ECT sensor operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• DTCs P0116, P0117, P0118 and P0125 diagnostic table is developed with the assumption the engine cooling
system is functioning correctly. Therefore, rectify any engine cooling system fault conditions before proceeding
with this diagnostic table.
• Test the ECT sensor using the ECT Temperature vs. Resistance in 6C1-3 Engine Management –V6 – Service
Operations. If the engine has sat overnight, the ECT sensor should display within 3 °C of the IAT sensor values.
W hen the engine is first started, the ECT should rise steadily to about 90 °C then stabilise when thermostat opens.
• 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 A fault condition in the engine cooling system may trigger these DTCs.
7 The ECT sensor low reference circuit is shared with other components. DTC P0118 may set if the shared low reference circuit is shorted to voltage. Test the low reference circuit of all components that share this circuit to find
the source of the fault condition.
DTC P0116, P0117, P0118, P0125 and P1258 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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Engine Management – V6 – Diagnostics Page 6C1-2–77

Step Action Yes No
2 Test the engine cooling system for correct operation. Refer to 6B1
Engine Cooling – V6.
W as any fault found and rectified? Go to Step 10 Go to Step 3
3 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 P0116, P0117, P0118, P0125 or P1258 fail this ignition
cycle? Go to Step 4 Refer to Additional
Information in this DTC
4 1 Switch off the ignition.
2 Disconnect the ECT sensor wiring connector.
3 Switch on the ignition with the engine not running.
4 Using a digital multimeter, measure the voltage between the ECT sensor signal circuit and the ECM housing.
Does the multimeter display 4.8 – 5.2 V? Go to Step 5 Go to Step 6
5 1 Switch off the ignition.
2 Remove ECM Fuse 29 from the engine compartment fuse and relay panel assembly.
3 Using a digital multimeter, measure the resistance between the ECT 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 8 Go to Step 7
6 Test the IAT sensor signal circuit 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 any fault found and rectified? Go to Step 10 Go to Step 9
7 Test the ECT sensor low reference circuit 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.
NOTE
The ECT sensor shares the low reference circuit with other
sensors. A fault condition in the low reference circuit may
trigger DTCs on sensors that share this circuit. Refer to 3
W iring Diagrams and Connector Charts in this
Section, to assist diagnosis.
W as any fault found and rectified? Go to Step 10 Go to Step 9
8 Replace the ECT sensor. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 10 —
9 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 10 —

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Engine Management – V6 – Diagnostics Page 6C1-2–79

• The TP sensor 2 signal voltage is 0.15 – 4.8 V.
DTC P0222 runs continuously once the following conditions are met:
• The battery voltage is greater than 7 V.
• The ignition is switched on.
Conditions for Setting the DTC
DTC P0121
The following conditions exist:
• The TP sensor 1 signal voltage and the TP sensor 2 signal voltage have a difference of greater than 9 percent.
• The TP sensor signal voltage has a difference of greater than 9 percent from the calculated TP sensor signal
voltage.
DTC P0122
The ECM detects the TP sensor 1 signal voltage is less than 0.18 volt.
DTC P0123
The ECM detects the TP sensor 1 signal voltage is greater than 4.6 V.
DTC P0221
The following conditions exist:
• The TP sensor 2 signal voltage and the TP sensor 1 signal voltage have a difference of greater than 9 percent.
• The TP sensor 2 signal voltage has a difference of greater than 9 percent from the calculated TP sensor signal
voltage.
DTC P0222
The ECM detects the TP sensor 2 signal voltage is less than 0.16 volt.
DTC P0223
The ECM detects the TP sensor 2 signal voltage is greater than 4.8 V.
Conditions for Clearing the DTC
DTCs P0121, P0122, P0123, P0221, P0222 are P0223 are Type B DTCs. 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 TP sensor operation.
• The ECM defaults to a reduced power mode if there is a fault condition in the TP sensor circuits for the entire
ignition cycle, even if the fault condition is corrected.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• The TP sensors share a common 5 V reference circuit, test for a fault condition in the 5 V reference circuit if both
DTCs P0122 and P0222 are 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.

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Engine Management – V6 – Diagnostics Page 6C1-2–86

DTC P2243 and P2247
The ECM detects the internal HO2S signal voltage is not 0.2 – 4.7 V.
DTC P2270 and P2272
W hen the ECM detects the HO2S 2 is less than 650 mV for 100 seconds, the ECM enriches the fuel mixture up to 30
percent for 10 seconds. This DTC sets if the ECM detects the HO2S 2 is still less than 650 mV.
DTC P2271 and P2273
W hen the ECM detects the HO2S 2 is greater than 650 mV for 100 seconds, the ECM leans the fuel mixture up to -7
percent for 10 seconds. If this signal voltage is still greater than 650 mV, the ECM tests the HO2S at the next decel fuel
cut-off. This DTC sets if the ECM detects the HO2S 2 signal voltage is greater than 200 mV after 4 seconds in decel fuel
cu-off mode.
DTC P2297 and P2298
The ECM detects the internal HO2S 1 signal voltage is greater than 3.7 V for longer than 10 seconds.
Conditions for Clearing the DTC
The HO2S reference circuit DTCs are Type B DTCs. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action
taken when 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 HO2S system operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• The HO2S must be tightened correctly. A loose HO2S will trigger these DTCs.
• A fault condition in the fuel delivery system, air intake system or exhaust system may trigger these DTCs.
• 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.
DTC P0130 to P0132, P0135 to P0138, P0140, P0141, P0150 to P0152, P0155, P0157, P0158,
P0160, P0161, P2243, P2247, P2270 to P2273, P2297 or P2298 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 Start the engine.
3 Allow the engine to reach the normal operating temperature.
4 Increase the engine speed to 2,000 rpm for 10 seconds or operate the vehicle within the conditions for setting the DTC.
5 Using Tech 2, select the DTC display function.
Does DTC P0130, P0131, P0132, P0135, P0137, P0138, P0140,
P0141, P0150, P0151, P0152, P0155, P0160, P0161, P2243, P2247,
P2270, P2271, P2272, P2273, P2297 or P2298 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 Are DTCs relating to the heater circuit of the O2 sensor, also set?
(e.g. P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051,
P0052, P0056, P0057 or P0058) Go to the
appropriate DTC
Table in this Section Go to Step 4

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Engine Management – V6 – Diagnostics Page 6C1-2–89

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission
related diagnostic.
• Use Tech 2 to clear the MIL/DTC.
Additional Information
• Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a
component harness connector.
• The lower connector of the ECM is connector A43-X1 and the upper connector of the ECM is connector A43-X2.
Refer to 3 W iring Diagrams and Connector Charts in this Section.
• The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be
relatively stable for an idling engine.
• 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.
• The following table illustrates the typical voltages for the HO2S circuits:
HO2S Voltages
Conditions: • Ignition ON, Engine OFF
• HO2S Disconnected
HO2S Circuit Voltage
Heater Control 4.6 – 5.0 V
Heater Supply Voltage B+
Reference Voltage 2.6 – 3.1 V
Low Reference 2.2 – 2.7 V
Pump Current Less than 0.5 A
Input Pump Current Less than 0.5 A
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2 This step determines if the condition exists.
4 This step determines if the fuel system is contaminated.
DTC P0133 or P0153 Diagnostic Table
Step Action Yes No
1
Has the Diagnostic System Check been completed? Go to Step 2 Refer to
4.4 Diagnostic System Check

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