lock ISUZU TF SERIES 2004 Workshop Manual

6E–120 ENGINE DRIVEABILITY AND EMISSIONS
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
If these codes are also set, it could indicate a
problem with the 5 Volt reference circuit.
Damaged harness - Inspect the wiring harness fordamage, short to ground, short to battery positive,
and open circuit. If the harness appears to be OK,
observe the MAP display on the Tech 2 while moving
connectors and wiring harnesses related to the
sensor. A change in the display will indicate the
location of the fault.
Diagnostic Trouble Code (DTC) P0107
Manifold Absolute Pressure Circuit Low Input
Step A ction Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0:
Diagnostic Trouble Code”.
Is the DTC P0107 stored as “Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”.
2. Select “Clear DTC Information” with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed
This Ignition” in “F2: DTC Information”.
Was the DTC P0107 stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the MAP sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Visually check the MAP.
Was the problem found? —Go to Step 9 Go to Step 6
6 Using the DVM and check the MAP sensor power
supply circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the MAP sensor connector.
3. Check the circuit for open or short to ground
circuit.
Was the DVM indicated specified value?
Approx imately
5.0V Go to Step 8Go to Step 7
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6E–124 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
If these codes are also set, it could indicate aproblem with the 5 Volt reference circuit.
Damaged harness - Inspect the wiring harness for
damage; an open circuit, a short to ground, or a short
to voltage. If the harness appears to be OK, observe
the MAP display on the Tech 2 while moving
connectors and wiring harnesses related to the
sensor. A change in the display will indicate the
location of the fault.
Diagnostic Trouble Code (DTC) P0108
Manifold Absolute Pressure Circuit High Input
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0:
Diagnostic Trouble Code”.
Is the DTC P0108 stored as “Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”.
2. Select “Clear DTC Information” with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed
This Ignition” in “F2: DTC Information”.
Was the DTC P0108 stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the MAP sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Visually check the MAP sensor.
Was the problem found?—Go to Step 11Go to Step 6
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ENGINE DRIVEABILITY AND EMISSIONS 6E–127
DIAGNOSTIC TROUBLE CODE (DTC) P0112 INTAKE AIR TEMPERATURE
SENSOR LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The engine control module (ECM) applies 5
volts through a pull-up resistor to the IAT sensor. When
the intake air is cold, the sensor resistance is high and
the ECM will monitor a high signal voltage on the IAT
signal circuit. If the intake air is warm, the sensor
resistance is lower, causing the ECM to monitor a lower
voltage. Diagnostic Trouble Code P0112 will set when
the ECM detects an ex cessively low signal voltage(short to ground) on the intake air temperature sensor
signal circuit.
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
Damaged harness - Inspect the wiring harness for
damage, short to ground, short to battery and open
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0112 A Intake Air Temperature Sensor Low
Input1. No DTC re lating to VSS.
2. Vehicle spe ed is mo re tha n 25km/h.
3. Engine run time is longer than 120 sec-
onds.
4. IAT sensor output is more than 149 deg. C. The ECM uses 20 de g. C conditio n as
substitute.

ENGINE DRIVEABILITY AND EMISSIONS 6E–131
DIAGNOSTIC TROUBLE CODE (DTC) P0113 INTAKE AIR TEMPERATURE
SENSOR HIGH INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The engine control module (ECM) applies 5
volts through a pull-up resistor to the IAT sensor. When
the intake air is cold, the sensor resistance is high and
the ECM will monitor a high signal voltage on the IAT
signal circuit. If the intake air is warm, the sensor
resistance is lower causing the ECM to monitor a lowervoltage. Diagnostic Trouble Code P0113 will set when
the ECM detects an ex cessively high signal voltage on
the intake air temperature sensor signal circuit.
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0113 A Intake Air Temperature Sensor High
Input1. No DTC re lating to VSS & ECT se nso r.
2. Vehicle speed is below 70km/h.
3. 3Engine coolant temperature is more than -
8 deg. C.
4. Engine run time is longer than 120 sec-
onds.
5. Ma ss a ir flo w is below 30g/s.
6. IAT sensor output is below -38 deg. C. The ECM uses 20 de g. C conditio n as
substitute.

6E–136 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0117 ENGINE COOLANT
TEMPERATURE SENSOR LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine coolant temperature (ECT) sensor is a
thermistor mounted in the engine coolant stream. The
engine control module (ECM) applies a voltage (about 5
volts) through a pull-up resistor to the ECT signal circuit.
When the engine coolant is cold, the sensor (thermistor)
resistance is high, therefore the ECM will measure a
high signal voltage. As the engine coolant warms, the
sensor resistance becomes lower, and the ECT signal
voltage measured at the ECM drops. Diagnostic Trouble
code P0117 set when the ECM detects an ex cessively
low signal voltage on the engine coolant temperature
sensor signal circuit.
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
Damaged harness - Inspect the wiring harness for
damage, short to ground, short to battery positive,
and open circuit. If the harness appears to be OK,
observe the ECT display on the Tech 2 while moving
connectors and wiring harnesses related to the ECT
sensor. A change in the ECT display will indicate the
location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0117 A Engine Coolant Temperature Sensor
Lo w Input1. Engine run time is longer than 120 sec-
onds.
2. ECT sensor output is more than 149 deg.
C. The ECM uses default engine coolant
temperature value based on intake air
temperature and engine run time.

ENGINE DRIVEABILITY AND EMISSIONS 6E–139
DIAGNOSTIC TROUBLE CODE (DTC) P0118 ENGINE COOLANT
TEMPERATURE SENSOR HIGH INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The engine coolant temperature (ECT) sensor is a
thermistor mounted in the engine coolant stream. The
engine control module (ECM) applies a voltage (about 5
volts) through a pull-up resistor to the ECT signal circuit.
When the engine coolant is cold, the sensor (thermistor)
resistance is high, therefore the ECM will measure a
high signal voltage. As the engine coolant warms, the
sensor resistance becomes less, and the ECT signal
voltage measured at the ECM drops. Diagnostic Trouble
code P0118 set when the ECM detects an ex cessively
high signal voltage on the engine coolant temperature
sensor signal circuit.
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
Damaged harness - Inspect the wiring harness for
damage, short to ground, short to battery positive,
and open circuit. If the harness appears to be OK,
observe the ECT display on the Tech 2 while moving
connectors and wiring harnesses related to the ECT
sensor. A change in the ECT display will indicate the
location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0118 A Engine Coolant Temperature Sensor
High Input1. Engine run time is longer than 120 sec-
onds.
2. ECT sensor output is below -38 deg.C. The ECM uses default engine coolant
temperature value based on intake air
temperature and engine run time.

ENGINE DRIVEABILITY AND EMISSIONS 6E–143
DIAGNOSTIC TROUBLE CODE (DTC) P0122 THROTTLE POSITION SENSOR
LOW INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The throttle position sensor circuit provides a signal
voltage that changes relative to throttle blade angle. The
signal voltage will vary from below 1 volt at closed
throttle to about 4 volts at wide open throttle (WOT).
The TPS signal is used by the engine control module
(ECM) for fuel control and most of the ECM-controlled
outputs. If the ECM detect a continuous short to ground
in the TPS or circuit, then a code P0122 will set.
Diagnostic Aids
Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
Damaged harness - Inspect the wiring harness for
damage, short to ground, short to battery positive,
and open circuit. If the harness appears to be OK,
observe the throttle position display on the Tech 2
while moving connectors and wiring harnesses
related to the TPS. A change in the display will
indicate the location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0122 A Throttle Position Sensor Low Input TPS output voltage is below 0.14V. The ECM uses 0% condition as substitute.

ENGINE DRIVEABILITY AND EMISSIONS 6E–147
DIAGNOSTIC TROUBLE CODE (DTC) P0123 THROTTLE POSITION SENSOR
HIGH INPUT
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The throttle position sensor circuit provides a voltage
signal that changes relative to throttle blade angle. The
signal voltage will vary from below 1 volt at closed
throttle to about 4 volts at wide open throttle (WOT).
The TPS is used by the engine control module (ECM)
for fuel control and most of the ECM-controlled outputs.
If the ECM detect a continuous short voltage in the TPS
or circuit, then a code P0123 will set.
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM - Inspect harnessconnectors for backed-out terminals, improper
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
If these codes are also set, it could indicate a
problem with the 5 Volt reference circuit or
components itself.
Damaged harness - Inspect the wiring harness for
damage, short to ground, short to battery positive and
open circuit. If the harness appears to be OK,
observe the Throttle Position sensor display on the
Tech 2 while moving connectors and wiring
harnesses related to the TP sensor. A change in the
display will indicate the location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P0123 A Throttle Po sition Se nsor High Input TPS output v olta ge is mo re tha n 4.9V. The ECM uses 0% co nditio n as substitute.

6E–152 ENGINE DRIVEABILITY AND EMISSIONS
Poor ECM to engine block grounds.
Fuel pressure - The system will go lean if pressure is
too low. The ECM can compensate for some
decrease. However, if fuel pressure is too low, a
Diagnostic Trouble Code P0131 may be set. Refer to
Fuel System Diagnosis.
Lean injector(s) - Perform “I njector Balance Test.”
Vacuum leaks - Check for disconnected or damaged
vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV
system.Ex haust leaks - An ex haust leak may cause outside
air to be pulled into the ex haust gas stream past the
HO2S, causing the system to appear lean. Check for
exhaust leaks that may cause a false lean condition
to be indicated.
Fuel contamination - Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean ex haust to be indicated. Ex cessive
alcohol in the fuel can also cause this condition. For
the procedure to check for fuel contamination, Refer
to Fuel System Diagnosis.
Diagnostic Trouble Code (DTC) P0131
O
2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
Step A ction Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Connect the Tech 2.
2. Review and record the failure information.
3. Select “F0: Read DTC Infor By Priority” in “F0:
Diagnostic Trouble Code”.
Is the DTC P0131 stored as “Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech2, ignition “On” and engine “Off”.
2. Select “Clear DTC Information” with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F5: Failed
This Ignition” in “F2: DTC Information”.
Was the DTC P0131 stored in this ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Check for poor/faulty connection at the O
2 sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
—Verify repair Go to Step 5
5 Using the DVM and check the O
2 sensor circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the O
2 sensor connector.
3. Check the circuit for short to heater ground or
ground circuit.
Was the DVM indicated specified value?
Approximatly
450mV Go to Step 7Go to Step 6
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6E–154 ENGINE DRIVEABILITY AND EMISSIONS
9 1. Using the Tech 2, ignition “On” and engine “On”.
2. Monitor the “Manifold Absolute Pressure” in the
data display.
Does the Tech 2 indicate correct “Manifold Absolute
Pressure” in accordance with engine speed or
acceleration? —Go to Step 11Go to Step 10
10 Remove the MAP sensor and check for the following
conditions.
Objects blocking the air cleaner.
Objects blocking the MAP sensor.
Objects blocking the throttle valve.
Vacuum leaking at intake duct.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 11
11 1. Using the Tech 2, ignition “On” and engine “On”.
2. Select the “Miscellaneous Test” and perform the
“IAC Control” in the “IAC System”.
3. Operate the Tech 2 in accordance with procedure.
Was the engine speed changed, when the IAC valve
is operating step by step?—Go to Step 13Go to Step 12
12 Check for the following conditions.
Objects blocking the IAC valve.
Objects blocking the throttle valve.
Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 13
13 Check for injector for the affected bank.
Refer to “Injector Coil Test & Injector Balance Test
Procedure” 6E-98 page.
Was the injector operation correct?
—Go to Step 14Refer to Injector
Coil Test &
Injector
Balance Test
Procedure
14 Check for fuel pressure.
Refer to “Fuel System Diagnosis” 6E-108 page.
Was the fuel pressure correct? —Go to Step 15Refer to Fuel
System
Diagnosis
15 Replace the O
2 sensor.
Was the problem solved?—Verify repair Go to Step 16
16 Is the ECM programmed with the latest software
release?
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”.
Was the problem solved?—Verify repair Go to Step 17
17 Replace the ECM.
Is the action complete?
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual.
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.—Veri fy repai r— Step A ction Value(s) Yes No