cooling ISUZU KB P190 2007 Workshop Repair Manual

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 6C1-2–91

Step Action Yes No
7 NOTE
If both DTCs are set, determine and correct the cause of
the contamination before replacing a sensor.
1 Inspect for the following conditions:
• Fuel contamination – refer to 6.5 Alcohol / Contaminants
in Fuel Diagnosis in this Section.
• The correct RTV sealant.
• Engine oil consumption – refer to 6A1 Engine Mechanical
– V6.
• Engine coolant consumption – refer to 6B1 Engine Cooling
– V6.
2 Replace the HO2S. Refer to 6C1-3 Engine Management – V6 – Service Operations.
Did you complete the replacement? Go to Step 8 —
8 1 Use Tech 2 to Clear the DTCs.
2 Turn OFF the ignition for 30 seconds.
3 Start the engine.
4 Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you
observed from the Freeze Frame / Failure Records.
Did the DTC fail this ignition? Go to Step 2 Go to Step 9
9 1 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, clear all DTCs and verify correct operation
7.12 DTC P0139 or P0159
DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC P0139 – O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
• DTC P0159 – O2 Sensor Circuit Slow Response (Bank 2 Sensor 2)
Circuit Description
The post catalytic converter heated oxygen sensor (HO2S) produces a voltage that varies between 100 – 900 mV under
normal operating conditions. The engine control module (ECM) produces a bias voltage on the HO2S signal circuit of
420 – -480 mV. The reference ground for the sensor is provided through the ECM.
The ECM monitors the signal voltage to determine if the exhaust is lean or rich. The oxygen sensor voltage is high when
the exhaust is rich, and low when the exhaust is lean. The ECM constantly monitors the HO2S signal during the Closed
Loop operation. If the ECM detects that the decel fuel cut-off rich-to-lean transition time is too long, DTC P0139 will set
for bank 1 sensor 2, or DTC P0159 will set for bank 2 sensor 2.
Conditions for Running the DTC
• DTCs P0021, P0024, P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058,
P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128,
P0131, P0132, P0135, P0137, P0138, P0139, P0140, P0141, P0151, P0152, P0155, P0157, P0158, P0159,
P0160, P0161, P0201-P0208, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270,
P0271, P0273, P0274, P0276, P0277, P0279, P0280, P0282, P0283, P0300, P0301-P0308, P0335, P0336,

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Engine Management – V6 – Diagnostics Page 6C1-2–96

• 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:
5 Test signal circuit of the EOT sensor. This circuit should display a voltage within the specified range.
6 Measures the integrity of the EOT sensor low reference circuit. Removal of the Fuse 29 enables the ECM to power down completely prior to the test procedure.
DTC P0196, P0197 or P0198 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 Test the engine cooling system for correct operation. Refer to 6B1
Engine Cooling – V6.
W as any fault found and rectified? Go to Step 11 Go to Step 3
3 Inspect the engine oil condition. Refer to 6A1 Engine Mechanical –
V6.
W as any fault found and rectified? Go to Step 11 Go to Step 4
4 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 P0196, P0197 or P0198 fail this ignition cycle? Go to Step 5 Refer to Additional
Information in this DTC
5 1 Switch off the ignition.
2 Disconnect the EOT sensor wiring connector.
3 Switch on the ignition with the engine not running.
4 Using a digital multimeter, measure the voltage between the EOT sensor signal circuit and the ECM housing.
Does the multimeter display 4.8 – 5.2 V? Go to Step 6 Go to Step 7
6 1 Switch off the ignition.
2 Remove ECM / TCM Fuse 29 from the engine compartment fuse and relay panel assembly.
3 Using a digital multimeter, measure the resistance between the EOT 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 9 Go to Step 8
7 Test EOT 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 11 Go to Step 10

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Engine Management – V6 – Diagnostics Page 6C1-2–128

Step Action Yes No
10 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.
7.26 DTC P0480, P0691 or P0692
DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC P0480 – Cooling Fan Relay 1 Circuit Malfunction
• DTC P0691 – Cooling Fan Relay 1 Circuit Low Voltage
• DTC P0692 – Cooling Fan Relay 1 Circuit High Voltage
Circuit Description
The engine control relay applies ignition positive battery voltage to the ignition circuit of the engine cooling fan relay 1
and relay 2. Using a device called a driver, the ECM performs the following tasks:
• grounds the engine cooling fan relay 1 control signal circuit to operate the small engine cooling fan, or
• grounds the engine cooling fan relay 2 control signal circuit to operate both the small engine cooling fan and the
large engine cooling fan.
The driver has a feedback circuit that is pulled-up to a voltage. The ECM monitors the driver feedback circuit to
determine if the control circuit is open, shorted to ground or shorted to a positive voltage.
A cooling fan relay control circuit DTC sets if the ECM detects a fault condition in the engine cooling fan relay control
circuit.
Conditions for Running the DTC
Run continuously once the following conditions are met:
• the ignition voltage is 10 – 16 V,
• the engine speed is greater than 40 rpm, and
• the ECM driver transitions from on to off or from off to on.
Conditions for Setting the DTC
DTC P0480
The ECM detects an open circuit fault condition in the control circuit of the engine cooling fan relay 1.
DTC P0691
The ECM detects a short to ground fault condition in the control circuit of the engine cooling fan relay 1.
DTC P0692
The ECM detects a short to voltage fault condition in the control circuit of the engine cooling fan relay 1.
Conditions for Clearing DTC
The cooling fan relay control circuit DTCs are Type B DTCs. Refer to 1.4 Diagnostic Trouble Codes in this Section, for
action taken when Type B DTCs set and conditions for clearing Type B DTCs.
Additional Information
• Refer to 6B1 – Engine Cooling – V6 for details of the engine cooling fan operation.

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Engine Management – V6 – Diagnostics Page 6C1-2–129

• 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.
DTC P0480, P0691 & P0692 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 P0480, P0691 or P0692 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 1 Remove the appropriate engine cooling fan relay. Refer to 8A
Electrical-Body and Chassis.
2 Connect a test lamp between the ignition voltage circuit of the engine cooling fan relay and the ECM housing.
3 Switch on the ignition with the engine not running.
Does the test lamp illuminate? Go to Step 4 Go to Step 5
4 1 Switch off the ignition.
2 Connect a test lamp between the control circuit of the appropriate engine cooling fan relay and a 12 V.
3 Switch on the ignition with the engine not running.
4 Using Tech 2, command the appropriate engine cooling fan relay on and then off.
Does the test lamp turn on and off when the engine cooling fan relay
is commanded on and off? Go to Step 7 Go to Step 6
5 Repair the high resistance or open circuit fault condition in the ignition
voltage circuit of the engine cooling fan relay. Refer to 8A Electrical -
Body and Chassis for information on electrical wiring repair
procedures.
W as the repair completed? Go to Step 9 —
6 Test the engine cooling fan relay control 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
7 Replace the faulty engine cooling fan relay. Refer to 8A Electrical-
Body and Chassis.
W as the repair completed? Go to Step 9 —

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Engine Management – V6 – Diagnostics Page 6C1-2–130

Step Action Yes No
8 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 9 —
9 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 cooling fan relay control circuit DTCs fail this ignition
cycle? Go to Step 2 Go to Step 10
10 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.
7.27 DTC P0500
DTC Descriptor
This diagnostic procedure supports DTC P0500 – Vehicle Speed Sensor Circuit Malfunction (Manual Transmission).
Circuit Description
Vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The
ignition control relay applies ignition positive voltage to the VSS, and the ground circuit of the VSS is directly connected
to ground.
The VSS is a Hall effect switch. In conjunction with an 18 tooth reluctor wheel, the VSS provide a signal voltage to the
ECM. The ECM uses this signal voltage to determine vehicle speed.
If the ECM detects no vehicle speed, while other sensors indicate that the vehicle is moving, then DTC P0500 sets.
Conditions for Running the DTC
Runs once the following conditions are met:
• The engine coolant temperature is greater than 40º C,
• the ECM is in fuel shut-off mode, and
• the engine speed is between 1,520 and 3,520 rpm
Conditions for Setting the DTC
The ECM detects a speed of less than 0 km/h for 8 seconds continuously, or 50 seconds cumulative.
Conditions for Clearing the DTC
The vehicle speed sensor circuit malfunction DTC is a Type C DTC. 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.
• Refer to 6C1-1 Engine Management – V6 – General Information for details on:
• VSS operation, and
• fuel shut-off mode.

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Engine Management – V6 – Diagnostics Page 6C1-2–144

Step Action
Yes No
8 1 Disconnect the ECM wiring connector.
2 Test the EOP sensor low reference circuit for a high resistance and open circuit fault condition. Refer to 8A Electrical - Body
and Chassis for information on electrical fault diagnosis.
NOTE
The EOP 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 11 Go to Step 10
9 Replace the EOP sensor. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 11 —
10 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 11 —
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 for the engine oil pressure sensor circuit DTCs s 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.
7.32 DTC P0532 or P0533
DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC P0532 – A/C Pressure Sensor Voltage Low
• DTC P0533 – A/C Pressure Sensor Voltage High
Circuit Description
The ECM supplies a positive 5 V reference voltage to the air-conditioning (A/C) refrigerant pressure sensor through
reference circuit and the ground through the low reference circuit.
The A/C pressure sensor provides signal voltage to the ECM through the signal circuit that is proportional to the A/C
refrigerant pressure. The ECM monitors the signal voltage of the A/C pressure sensor to determine the refrigerant
pressure.
• The A/C pressure sensor voltage increases as the refrigerant pressure increases.
• W hen the ECM detects the refrigerant pressure exceeds a predetermined value, the ECM activates the cooling
fans to reduce the refrigerant pressure.
• W hen the ECM detects the refrigerant pressure is too high or too low, the ECM disables the A/C clutch to protect
the A/C compressor from damage.

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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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Engine Management – V6 – Diagnostics Page 6C1-2–227

Knock Retard Cylinder 3 °CA 0 0
Knock Retard Cylinder 4 °CA 0 0
Knock Retard Cylinder 5 °CA 0 0
Knock Retard Cylinder 6 °CA 0 0
Ignition Accessory Signal Off / On On On
Ignition On Signal Off / On On On
Malfunction Indicator (MI) Off / On / Flashing On Off
Fuel Pump Relay Off / On Off On
Engine Control Ignition Relay Off / On On On
Engine Control Ignition Relay Feedback V 11.5 14.1
(1) Actual Gear -1- / -2- / -3- / -4- / -
5- / -P/N- / -R- / -Invalid- -P/N- -P/N-
Brake Lamp Switch
Inactive / Active Inactive Inactive
Reduced Engine Power Inactive / Active Inactive Inactive
DTC Set This Ignition No DTC / DTC Set No DTC No DTC
Vehicle Speed km/h 0 0
Engine Runtime h:m:s 00:00:00 00:05:20
(2) Clutch Pedal Switch Inactive / Active Inactive Inactive
(1) Automatic Transmission Only (2) Manual Transmission Only
Engine Data 2
Tech 2 Display
Units Displayed Ignition On Engine Running
Engine Speed RPM 0 751
Desired Engine Idle Speed RPM 830 750
Coolant Temperature °C 21 78
Cooling Fan On/Off Off On
Calculated ECT – Closed Loop Fuel Control (Engine
Coolant Temperature) °C 21 37
Calculated ECT – Thermostat Diagnosis (Engine
Coolant Temperature) °C 22 78
Intake Air Temperature
°C 31 27
Start Up ECT (Engine Coolant Temperature) °C 21 21
Start Up IAT (Intake Air Temperature) °C –48 30
Mass Air Flow Sensor V 1.00 1.3
Mass Air Flow g/s 0.00 5.47
Engine Load % 100 25
Volumetric Efficiency % 99 19
Power Enrichment No / Yes No No
Dec. Fuel Cutoff (Deceleration) Inactive / Active Inactive Inactive
Calculated Pedal Position % 0 0

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