1998 ISUZU TROOPER OBD port

6E±111 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0103 ± MAF Sensor Circuit High Frequency

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. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor ªDTCº info for DTC P0103.
Does the Tech 2 indicate DTC P0103 failed this
ignition?
ÐGo to Step 3
Refer to
Diagnostic
Aids
31. Start the engine.
2. With the engine idling, monitor ªMAF Frequencyº
display on the Tech 2.
Is ªMAF Frequencyº above the specified value?
219 g/SecGo to Step 4Go to Step 7
41. Ignition ªOFF.º
2. Disconnect the MAF sensor connector.
3. Ignition ªON,º engine idling.
4. Using a Tech 2, monitor ªMAF Frequency.º
Does the Tech 2 indicate a ªMAF Frequencyº at the
specified value?
0.0 g/SecGo to Step 5Go to Step 6
5Replace the MAF sensor.
Is the action complete?
ÐVerify repairGo to Step 8
61. Check the MAF harness for incorrect routing near
high voltage components (solenoids, relays,
motors).
2. If incorrect routing is found, correct the harness
routing.
Was a problem found?
ÐVerify repairGo to Step 7
71. With the engine idling, monitor ªMAF Frequencyº
display on the Tech 2.
2. Quickly snap open throttle to wide open throttle
while under a road load and record value.
Does the Tech 2 indicate ªMAF Frequencyº above the
specified value?
219 g/SecGo to Step 5Go to Step 8
8Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±120
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0112±IAT Sensor Circuit 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. Using a Tech 2, monitor the intake air temperature
(IAT).
Is the intake air temperature greater than the specified
value?
148
C
(283
F)
Go to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF.º Review and record
Tech 2 Failure Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor the ªSpecific DTCº info for
DTC P0112.
Does the Tech 2 indicate DTC P0112 failed this
ignition?
Ð
Refer to Test
Description
Refer to
Diagnostic
Aids
41. Ignition ªOFF.º
2. Disconnect the IAT sensor electrical connector.
3. Ignition ªON.º
4. Observe the intake air temperature on the Tech 2.
Is the intake air temperature below the specified value?
±38
C
(±36
F)
Go to Step 6Go to Step 5
51. Ignition ªOFF.º
2. Disconnect the PCM electrical connectors.
3. Check the IAT sensor signal circuit for a short to
ground.
Is the IAT sensor signal circuit shorted to ground?
ÐVerify repairGo to Step 7
6Replace the IAT 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±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±140
ENGINE DRIVEABILITY AND EMISSIONS
HO2S, causing the system to appear lean. Check for
exhaust leaks that may cause a false lean condition to
be indicated.

MAF sensor ± The system can go lean if the MAF
sensor signal indicates an engine airfiow
measurement that is not correct. Disconnect the MAF
sensor to see if the lean condition is corrected. If so,
replace the MAF sensor.

Fuel contamination ± Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessive
alcohol in the fuel can also cause this condition. Refer
to
Fuel System Diagnosis for the procedure to check
for fuel contamination.

If none of the above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to step numbers on the diagnostic
chart.
3. DTC P0131 failing during operation may indicate a
condition described in the ªDiagnostic Aidsº above.
If the DTC P0131 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0131 ±HO2S Circuit Low Voltage Bank 1 Sensor 1

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within the parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.
Does the Bank 1 HO2S 1 voltage remain below the
specified value?
22 mVGo to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF,º review and record Tech
2 Failure Records data and note parameters.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor ªSpecific DTCº info for DTC
P0131 until the DTC P0131 test runs.
Note test result.
Does Tech 2 indicate DTC P0131 failed this ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Turn the ignition ªOFF.º
2. Disconnect the PCM.
3. Check the Bank 1 HO2S 1 high and low circuits for a
short to ground or a short to the heater ground
circuit.
Are the Bank 1 HO2S 1 signal circuits shorted to
ground?
ÐGo to Step 5Go to Step 6
5Repair the Bank 1 HO2S 1 signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Turn the ignition ªOFF,º HO2S 1 and PCM
disconnected.
2. Check for continuity between the high and low
signal circuits.
Was there continuity between the high and low circuits?
ÐGo to Step 7Go to Step 8
7Repair the short between the high and low circuits.
Is the action complete?
ÐVerify repairÐ

6E±143 ENGINE DRIVEABILITY AND EMISSIONS

An intermittent TP sensor output will cause the system
to go rich due to a false indication of the engine
accelerating.

Shorted Heated Oxygen Sensor (HO2S) ±If the HO2S
is internally shorted, the HO2S voltage displayed on
the Tech 2 will be over 1 volt. Try disconnecting the
affected HO2S with the key ªON,º engine ªOFF.º If the
displayed HO2S voltage changes from over 1000 mV
to around 450 mV, replace the HO2S. Silicon
contamination of the HO2S can also cause a high
HO2S voltage to be indicated. This condition is
indicated by a powdery white deposit on the portion of
the HO2S exposed to the exhaust stream. If
contamination is noticed, replace the affected HO2S.

Open HO2S Signal Circuit or Faulty HO2S±A poor
connection or open in the HO2S signal circuit can
cause the DTC to set during deceleration fuel mode.
An HO2S which is faulty and not allowing a full voltage
swing between the rich and lean thresholds can also
cause this condition. Operate the vehicle by
monitoring the HO2S voltage with a Tech 2. If theHO2S voltage is limited within a range between 300
mV to 600 mV, check the HO2S signal circuit wiring
and associated terminal conditions.

If none of the above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0132 failing during ªdeceleration fuel cutoff
modeº operation may indicate a condition described
in the ªDiagnostic Aidsº above. If the DTC P0132
test passes while the Failure Records conditions are
being duplicated, an intermittent condition is
indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0132 ± HO2S Circuit High Voltage Bank 1 Sensor 1

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within parameters specified
under ªConditions for Setting the DTCº included in
Diagnostic Support.
4. Using a Tech 2, monitor Bank 1 HO2S 1 voltage.
Does the Bank 1 HO2S 1 voltage remain above the
specified value?
952 mV (500
mV in
deceleration
fuel cutoff
mode)
Go to Step 4Go to Step 3
31. Ignition ªON,º review and record Tech 2 Failure
Records data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor ªSpecific DTCº info for DTC
P0132 until the DTC P0132 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0132 failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Ignition ªOFF.º
2. Disconnect Bank 1 HO2S 1.
3. Ignition ªON.º
4. At HO2S Bank 1 Sensor 1 connector (PCM side)
use a DVM to measure voltages at the high and low
signal terminals.
Are the voltages in the specified range?
3-4 VGo to Step 5Go to Step 6
5Repair short to voltage in signal circuit.
Is the action complete?
ÐVerify repairÐ

6E±149 ENGINE DRIVEABILITY AND EMISSIONS
exhaust leaks that may cause a false lean condition to
be indicated.

MAF sensor ±The system can go lean if the MAF
sensor signal indicates an engine airflow
measurement that is not correct. Disconnect the MAF
sensor to see if the lean condition is corrected. If so,
replace the MAF sensor.

Fuel contamination ± Water, even in small amounts,
can be delivered to the fuel injectors. The water can
cause a lean exhaust to be indicated. Excessive
alcohol in the fuel can also cause this condition. Refer
to
Fuel System Diagnosis for the procedure to check
for fuel contamination.

If none of the above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0151 failing during operation may indicate a
condition described in the ªDiagnostic Aidsº above.
If the DTC P0151 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicate.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0151 ± HO2S Circuit Low Voltage Bank 2 Sensor 1

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install Tech 2.
2. Run the engine at operating temperature.
3. Operate the vehicle within the parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using Tech 2, monitor Bank 2 HO2S 1 voltage.
Does the Bank 2 HO2S 1 voltage remain below the
specified value?
22 mVGo to Step 4Go to Step 3
31. Ignition ªON,º engine ªOFF,º review and record Tech
2 Failure Records data and note parameters.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using Tech 2, monitor ªSpecific DTCº info for DTC
P0151 until the DTC P0151 test runs.
4. Note test result.
Does Tech 2 indicate DTC P0151 failed this ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Turn ignition ªOFF.º
2. Disconnect the PCM.
3. Check the Bank 2 HO2S 1 high and low signal
circuits for a short to ground or a short to the heater
ground circuit.
Were Bank 2 HO2S 1 signal circuits shorted?
ÐGo to Step 5Go to Step 6
5Repair the Bank 2 HO2S 1 signal circuit.
Is the action complete?
ÐVerify repairÐ
61. Ignition ªOFF.º
2. Leave the PCM and HO2S 1 disconnected.
3. Check for continuity between the high and low
signal circuits.
Was there continuity between the high and low circuits?
ÐGo to Step 7Go to Step 8
7Repair the short between the high and low circuits.
Is the action complete?
ÐVerify repairÐ

6E±152
ENGINE DRIVEABILITY AND EMISSIONS

MAF sensor ± The system can go rich if the MAF
sensor signal indicates an engine airflow
measurement that is not correct. Disconnect the MAF
sensor to see if rich condition is corrected. If so,
replace MAF sensor.

Check for leaking fuel pressure regulator diaphragm by
checking vacuum line to regulator for the presence of
fuel. There should be no fuel in the vacuum line.

TP sensor ± An intermittent TP sensor output will
cause the system to go rich, due to a false indication
of the engine accelerating.

Shorted Heated Oxygen Sensor (HO2S)± If the HO2S
is internally shorted, the HO2S voltage displayed on
Tech 2 will be over 1 volt. Try disconnecting the
affected HO2S with the key ªON,º engine ªOFF.º If the
displayed HO2S voltage changes from over 1000 mV
to around 450 mV, replace the HO2S. Silicon
contamination of the HO2S can cause a high HO2S
voltage to be indicated. This condition is indicated by
powdery white deposit on the portion of the HO2S
exposed to the exhaust stream. If contamination is
noticed, replace the affected HO2S.

Open HO2S Signal Circuit of Faulty HO2S± A poor
connection or open in the HO2S signal circuit can
cause the DTC to set during deceleration fuel mode.An HO2S which is faulty and not allowing a full voltage
switch between the rich and lean thresholds can also
cause the condition. Operate the vehicle while
monitoring the HO2S voltage with Tech 2. If the HO2S
is limited within a range between 300 mV to 600 mV,
check the HO2S signal circuit wiring and associated
terminal connections.

If none of the above conditions are present, replace the
affected HO2S.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. DTC P0152 failing during deceleration fuel cutoff
mode operation may indicate a condition described
in the ªDiagnostic Aidsº above. If the DTC P0152
test passes while the Failure Records conditions are
being duplicated, an intermittent condition is
indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
DTC P0152 ± HO2S Circuit High Voltage Bank 2 Sensor 1

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Install Tech 2.
2. Engine is at operating temperature.
3. Operate the vehicle within the parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
4. Using Tech 2, monitor Bank 2 HO2S 1 voltage.
Does the Bank 2 HO2S 1 voltage remain above the
specified value?
952 mV
(500 mV in
deceleration
fuel cut-off
mode)
Go to Step 4Go to Step 3
31. Ignition ªON.º
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using Tech 2, monitor ªSpecific DTCº info for DTC
P0152 until the DTC P0152 test runs.
5. Note the test result.
Does Tech 2 indicate DTC P0152 failed this ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Ignition ªOFF.º
2. Disconnect Bank 2 HO2S 1.
3. Ignition ªON.º
4. At HO2S Bank 2 Sensor 1 connector (PCM side)
use a DVM to measure voltages at the high and low
signal terminals.
Are the voltages in the specified range?
3-4 VGo to Step 5Go to Step 6
5Repair short to voltage in signal circuit.
Is the action complete?
ÐVerify repairÐ

6E±172
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0201 ± Injector 1 Control Circuit

 
StepNo Ye s Value(s) Action
71. Disconnect the PCM connector for the affected
injectors.
2. With a test light connected to B+, probe the affected
injector driver circuit.
Does the test light illuminate?
ÐGo to Step 8Go to Step 15
8Repair short to ground in the injector driver circuit.
Is the action complete?
Ð
Go to OBD
System
Check
Ð
91. Disconnect the injector test connector.
2. At the injector side of the harness, connect an
ohmmeter between the positive wire (red with blue
tracer) and the wire for cylinder 1 (green with white
tracer).
Does the ohmmeter indicate continuity?
ÐGo to Step 11Go to Step 10
10Repair the open injector harness wire or open injector.
Is the action complete?
ÐVerify repairÐ
11At the PCM side of the injector test connector, check
the green/white wire for a short to voltage.
Was there a short to voltage?
ÐGo to Step 12Go to Step 13
12Repair the short to voltage.
Is the action complete?
ÐVerify repairÐ
13Check for an open circuit between the injector test
connector and the PCM.
Was there an open circuit?
ÐGo to Step 14Go to Step 15
14Repair the open circuit.
Is the action complete?
ÐVerify repairÐ
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ