1998 ISUZU TROOPER check engine

6E±123 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0113 ±IAT Sensor Circuit High Voltage

 
StepNo Ye s Value(s) Action
6Check for poor connections at the IAT sensor and
replace terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 10
71. Ignition ªOFF.º
2. Disconnect the PCM, and check the IAT sensor
ground circuit for an open.
3. If the IAT sensor ground circuit is open, repair it as
necessary.
Was the IAT sensor ground circuit open?
ÐVerify repairGo to Step 9
81. Ignition ªOFF.º
2. Disconnect the PCM, and check the IAT signal
circuit for an open.
3. If the IAT sensor signal circuit is open, repair it as
necessary.
Was the IAT signal circuit open?
ÐVerify repairGo to Step 9
9Check for a poor sensor ground or IAT signal circuit
terminal connection at the PCM and replace
terminal(s) if necessary.
Did any of the terminals need to be replaced?
ÐVerify repairGo to Step 11
10Replace the IAT sensor.
Is the action complete?
ÐVerify repairÐ
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±124
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0117 ECT Sensor Circuit Low Voltage
060RY00304
Circuit Description
The engine coolant temperature (ETC) sensor is a
thermistor mounted on a coolant crossover pipe at the
rear of the engine. The powertrain control module (PCM)
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
PCM will measure a high signal voltage. As the engine
coolant warms, the sensor resistance becomes lower,
and the ECT signal voltage measured at the PCM drops.
With a fully warmed-up engine, the ECT signal voltage
should measure about 1.5 to 2.0 volts.
Conditions for Setting the DTC

Engine running time is longer than one minute.

The ECT sensor signal indicates an engine coolant
temperature greater than 150
C (302
F) (about 0.10
V) for a total of 50 seconds over a 100±second period.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

The PCM will substitute the ECT reading with a default
engine coolant temperature value. The default value
is based on start-up intake air temperature and running
time.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

DTC P0117 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:

Poor connection at PCM ± 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. 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.
If DTC P0117 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.

6E±126
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0117 ± ECT Sensor Low Voltage

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine ªOFF.º
2. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº below the specified value?
139
C
(282
F)
Go to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF.º
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªSpecific DTCº info for DTC
P0117.
Does the Tech 2 indicate DTC P0117 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Disconnect the ECT sensor electrical connector.
2. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº at the specified value?
±39
C
(±38
F)
Go to Step 6Go to Step 5
51. Ignition ªOFF.º
2. Disconnect the PCM and check the ECT signal
circuit for a short to ground or a short to the sensor
ground circuit.
3. If the ECT signal circuit is shorted. repair it as
necessary.
Was the ECT signal circuit shorted to ground?
ÐVerify repairGo to Step 7
6Replace the ECT sensor.
Is the action complete?
ÐVerify repairÐ
7Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±127 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0118 ECT Sensor Circuit High Voltage
060RY00304
Circuit Description
The engine coolant temperature (ETC) sensor is a
thermistor mounted in on a coolant crossover pipe at the
rear of the engine. The powertrain control module (PCM)
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
PCM will measure a high signal voltage. As the engine
coolant warms, the sensor resistance becomes less, and
the ECT signal voltage measured at the PCM drops. With
a fully warmed-up engine, the ECT signal voltage should
measure about 1.5 to 2.0 volts.
Conditions for Setting the DTC

Engine running time is longer than 1.5 minutes.

The ECT sensor signal indicates an engine coolant
temperature of ±39
C (±38
F) or less (about 5 volts)
for a total of 50 seconds over a 100-second period.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

The PCM will substitute the ECT reading with a default
engine coolant temperature value. The default value
is based on start-up intake air temperature and running
time.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC

DTC P0118 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
The ECT shares a ground with the Transmission Fluid
Temperature sensor, the Rough Road sensor, and the
MAP sensor.
Check the ground if these DTCs are also set.

Poor connection at PCM ± 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. 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.
If DTC P0118 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently,
performing the DTC P1115 Diagnostic Chart may isolate
the cause of the fault.

6E±128
ENGINE DRIVEABILITY AND EMISSIONS
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Verifies that the fault is present.
3. If DTC P0118 can be repeated only by duplicating
the Failure Records conditions, refer to the
ªTemperature vs. Resistance Valueº table. The
table may be used to test the ECT sensor at various
temperatures to evaluate the possibility of a
ªshiftedº sensor that may be shorted above or below
a certain temperature. If this is the case, replace
the ECT sensor. If the ECT sensor appears to be
OK, the fault is intermittent; refer to
Diagnostic Aids.
Engine Coolant Temperature Sensor

C
FOHMS
Temperature vs. Resistance Values
(approximate)
100212177
80176332
60140667
4511 31188
35951802
25772796
15594450
5417280
±52312300
±15521450
±30±2252700
±40±40100700
DTC P0118 ± ECT Sensor Circuit High Voltage

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine ªOFF.º
2. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº below the specified value?
±39
C
(±38
F)
Go to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF.º
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor the ªSpecific DTCº info for
DTC P0118.
Does the Tech 2 indicate DTC P0118 failed?
Ð
Refer to Test
Description
Refer to
Diagnostic
Aids
41. Disconnect the ECT sensor electrical connector.
2. Jumper the ECT signal circuit and the sensor
ground circuit together at the ECT sensor harness
connector.
3. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº at the specified value?
140
C
(284
F)
Go to Step 6Go to Step 5
51. Jumper the ECT signal circuit at the ECT sensor
harness connector to chassis ground.
2. Observe the ªEng Cool Tempº display on the Tech 2.
Is the ªEng Cool Tempº at the specified value?
140
C
(284
F)
Go to Step 7Go to Step 8
6Check for poor connections at the ECT sensor and
replace terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 10

6E±129 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0118 ± ECT Sensor Circuit High Voltage

 
StepNo Ye s Value(s) Action
71. Ignition ªOFF.º
2. Disconnect the PCM, and check the ECT sensor
ground circuit for an open.
3. If the ECT sensor ground circuit is open, repair it as
necessary.
Was the ECT sensor ground circuit open?
ÐVerify repairGo to Step 9
81. Ignition ªOFF.º
2. Disconnect the PCM, and check the ECT signal
circuit for an open.
3. If the ECT sensor signal circuit is open, repair it as
necessary.
Was the ECT signal circuit open?
ÐVerify repairGo to Step 9
9Check for a poor sensor ground or ECT signal circuit
terminal connection at the PCM and replace
terminal(s) if necessary.
Did any of the terminals need to be replaced?
ÐVerify repairGo to Step 11
10Replace the ECT sensor.
Is the action complete?
ÐVerify repairÐ
11Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±130
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0121 TP System Performance
D06RW028
Circuit Description
The throttle position (TP) sensor circuit provides a voltage
signal that changes relative to throttle blade angle. The
signal voltage will vary from about 0.6 volts at closed
throttle to about 4.5 volts at wide open throttle (WOT).
The TP signal is used by the powertrain control module
(PCM) for fuel control and many of the PCM-controlled
outputs. The PCM monitors throttle position and
compares actual throttle position from the TP sensor to a
predicted TP value calculated from engine speed. If the
PCM detects an out-of-range condition, DTC P0121 will
set.
Conditions for Setting the DTC

The engine is running.

No MAP DTCs, or P0121, P0122, P0123 are set.

MAP reading is below 55 kPa.

Throttle is steady, throttle angle is changing less than
1%.

Predicted throttle angle is not close to actual throttle
angle.

Above conditions are present for a total of 12.5
seconds over a 25-second period of time.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

The PCM will use a default throttle position based on
mass air flow and RPM.
Conditions for Clearing the MIL/DTC

DTC P0121 can be cleared by using the Tech 2 ªClear
info º function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:

Skewed MAP signal or faulty Map sensor ± An
incorrect MAP signal may cause the PCM to incorrectly
calculate the predicted TP sensor value during high
engine load situations. Check for an unusually low
MAP reading. This condition can cause DTC P0121 to
be set.

Poor connection at PCM ± 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. If the harness appears to be OK, observe the
ECT 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.
If DTC P0121 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E±131 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0121 ±TP System Performance

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Ignition ªON,º engine not running.
2. Observe the MAP reading on the Tech 2.
Is the MAP reading less than the specified value?
65 kPaGo to Step 3Go to Step 6
31. Disconnected the MAP sensor.
2. Connect a test light between the 5 volt reference ªAº
circuit and the MAP signal circuit at the MAP sensor
harness connector.
3. Observe the MAP reading on the Tech 2.
Is the MAP reading less than the specified value?
65 kPaGo to Step 5Go to Step 4
41. Check the MAP signal circuit between the PCM and
the MAP sensor for an open, short to ground, or
short to the MAP ground circuit.
2. If the MAP signal circuit is open or shorted, repair it
as necessary.
Was the MAP signal circuit open or shorted?
ÐVerify repairGo to Step 12
5Replace the MAP sensor.
Is the action complete?
ÐVerify repairÐ
6Observe the TP angle reading on the Tech 2 while
slowly opening the throttle.
Does the TP angle increase steadily and evenly from
the closed throttle value to the wide open throttle
value?Closed
throttle = 0%
Wide open
throttle =
100%
Refer to
Diagnostic
Aids
Go to Step 7
71. Disconnect the TP sensor.
2. Observe the TP sensor reading on the Tech 2.
Is the TP sensor reading near the specified value?
0 VGo to Step 8Go to Step 9
81. Connect a test light between the 5 volt reference ªAº
circuit and the TP sensor signal circuit at the TP
sensor harness connector.
2. Observe the TP sensor reading on the Tech 2.
Is the TP sensor reading at the specified value?
5 VGo to Step 11Go to Step 10
9Check the following items:
1. TP signal circuit for a short to voltage.
2. TP sensor ground circuit for high resistance
between the PCM and the TP sensor.
3. TP sensor ground circuit for a poor connection.
4. If a problem is found, repair wiring harness as
necessary.
Was a problem found?
ÐVerify repairGo to Step 12