1998 ISUZU TROOPER Service Repair Manual

spark plugs jacking points brake rotor interior lights seats remove seats

Page 1265 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±148
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0151 HO2S Circuit Low Voltage Bank 2
Sensor 1
060RW190
Circuit Description
The powertrain control module (PCM) supplies a bias

6E±148
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0151 HO2S Circuit Low Voltage Bank 2
Sensor 1
060RW190
Circuit Description
The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. When
measured with a 10 megaohm digital voltmeter, this may
display as low as 320 mV. The oxygen sensor varies the
voltage within a range of about 1000 mV when the
exhaust is rich, down through about 10 mV when exhaust
is lean. The PCM constantly monitors the HO2S signal
during ªclosed loopº operation and compensates for a rich
or lean condition by decreasing or increasing injector
pulse width as necessary. If the Bank 2 HO2S 1 voltage
remains excessively low for an extended period of time,
DTC P0151 will be set.
Conditions for Setting the DTC
No related DTCs.
The engine is operating in ªclosed loop.º
Engine coolant temperature is above 60C (140F).
ªClosed loopº commanded air/fuel ratio is between
14.5 and 14.8.
Throttle angle is between 3% and 19%.
Bank 2 HO2S 1 signal voltage remains below 22 mV
during normal ªclosed loopº operation for a total of 77
seconds over a 90-second period of time.
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 store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
ªOpen loopº fuel control will be in effect.
Conditions for Clearing the MIL/DTC
DTC P0151 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
Check for the following conditions:
Heated oxygen sensor wiring ± The sensor pigtail may
be mispositioned and contacting the exhaust system.
Poor PCM to engine block grounds.
Fuel pressure ± The system will go lean if pressure is
too low. The PCM can compensate for some
decrease. However, if fuel pressure is too low, a DTC
P0151 may be set. Refer to
Fuel System Diagnosis.
Lean injector(s) ± Perform ªInjector Balance Test.º
Vacuum leaks ± Check for disconnected or damaged
vacuum hoses and for vacuum leaks at the intake
manifold, throttle body, EGR system, and PCV system.
Exhaust leaks ± An exhaust leak may cause outside air
to be pulled into the exhaust gas stream past the
HO2S, causing the system to appear lean. Check for

Page 1266 of 3573

ISUZU TROOPER 1998 Service Repair Manual 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

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

Page 1267 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±150
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0151 ± HO2S Circuit Low Voltage Bank 2 Sensor 1
StepNo Ye s Value(s) Action
81. Ignition ªOFF.º
2. Reconnect the PCM, leave HO2S 2 disconnec

Page 1268 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±151 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0152 HO2S Circuit HIGH Voltage Bank 2
Sensor 1
060RW190
Circuit Description
The powertrain control module (PCM) supplies a bia

6E±151 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0152 HO2S Circuit HIGH Voltage Bank 2
Sensor 1
060RW190
Circuit Description
The powertrain control module (PCM) supplies a bias
voltage of about 450 mV between the heated oxygen
sensor (HO2S) signal high and signal low circuits. When
measured with a 10 megaohm digital voltmeter, this may
display as low as 320 mV. The oxygen sensor varies the
voltage within a range of about 1000 mV when the
exhaust is rich, down through about 10 mV when exhaust
is lean. The PCM constantly monitors the HO2S signal
during ªclosed loopº operation and compensates for a rich
or lean condition by decreasing or increasing the injector
pulse width as necessary. If the Bank 2 HO2S 1 voltage
remains excessively high for an extended period of time,
DTC P0152 will be set.
Conditions for Setting the DTC
No related DTCs.
The engine is operating in ªclosed loop.º
The engine coolant temperature is above 60C
(140F).
ªClosed loopº commanded air/fuel ratio between 14.5
and 14.8.
Throttle angle between 3% and 19%.
Bank 2 HO2S 1 signal voltage remains above 952 mV
during normal ªclosed loopº operation for a total of 77
seconds over a 90-second period.
ORBank 2 HO2S 1 signal voltage remains above 500 mV
during deceleration fuel cutoff mode operation for up to
3 seconds.
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 store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
ªOpen loopº fuel control will be in effect.
Conditions for Clearing the MIL/DTC
DTC P0152 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
Check for the following conditions:
Fuel pressure ± The system will go rich if pressure is
too high. The PCM can compensate for some
increase. However, if fuel pressure is too high, a DTC
P0152 may be set. Refer to
Fuel System Diagnosis.
Rich injector(s) ± Perform ªInjector Balance Test.º
Leaking injector ± Refer to
Fuel System Diagnosis.
Evaporative emissions (EVAP) system ± Check the
canister for fuel saturation. If the canister is full of fuel,
check EVAP control system components and hoses.
Refer to
Evaporative Emission (EVAP) Control
System.

Page 1269 of 3573

ISUZU TROOPER 1998 Service Repair Manual 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 i

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

Page 1270 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±153 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0152 ± HO2S Circuit High Voltage Bank 2 Sensor 1
StepNo Ye s Value(s) Action
61. Ignition ªON,º engineªOFF.º
2. At Bank 2 HO2S 1 connector

Page 1271 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±154
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0171 Fuel Trim System Lean Bank 1
D06RW030
Circuit Description
To provide the best possible combination of driveability,
fuel e

Page 1272 of 3573

ISUZU TROOPER 1998 Service Repair Manual 6E±155 ENGINE DRIVEABILITY AND EMISSIONS
Mass air flow is between 2 g/second and 200 g/second.
Ignition voltage is above 9.5 volts.
Fuel system is in ªclosed loop.º
Action Taken When the DTC Set

Load next 8 pages

Page: < prev 1-10 ... 1233-1240 1241-1248 1249-1256 1257-1264 1265-1272 1273-1280 1281-1288 1289-1296 1297-1304 ... 3576 next >

open hood roof rack open bonnet fuel reserve language parking sensors