1998 ISUZU TROOPER check engine

6E±242
ENGINE DRIVEABILITY AND EMISSIONS
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. A condition that affects other heated oxygen sensors
indicates probable contamination. To avoid
damaging replacement sensors, correct the
condition which caused the contamination before
replacing the affected sensors.5. This step checks for conditions which may cause the
heated oxygen sensor to appear faulty. Correct any
of the described conditions if present.
8. To avoid damaging replacement sensors, correct the
condition which caused the contamination before
replacing the affected sensors.
DTC P1154 ± HO2S Transition Time Ratio 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
2IMPORTANT:If any other DTCs are set (except P1133
and/or P1134), refer to those DTCs before proceeding
with this diagnostic chart.
1. Idle the engine at operating temperature.
2. Operate the vehicle within parameters specified
under ªConditions for Setting the DTCº criteria
included in Diagnostic Support.
3. Using a Tech 2, monitor ªSpecific DTCº info for DTC
P1154 until the DTC P1154 test runs.
Note the test result.
Does Tech 2 indicate DTC failed this ignition?
ÐGo to Step 3
Refer to
Diagnostic
Aids
3Did Tech 2 also indicate P1133, and/or P1134 test
failed?
ÐGo to Step 17Go to Step 4
4Check for leaks at the pipe joints.
Are the joints leaking?
ÐGo to Step 5Go to Step 6
5Tighten the U-bolt nuts at the leaking joints.
Is your action complete?
ÐGo to Step 2Ð
6Check for gaskets that are damaged or improperly
installed.
Are there damaged or misaligned gaskets?
ÐGo to Step 7Go to Step 8
71. Replace the damaged gaskets.
2. Align the connections.
3. Tighten the connections.
Is your action complete?
ÐGo to Step 2Ð
8Check for loose exhaust flange connections.
Are the flange connections loose?
ÐGo to Step 9Go to Step 10
9Tighten the stud nuts or bolts to specifications.
Is your action complete?
ÐGo to Step 2Ð
10Check for burned or corroded exhaust pipes.
Are the exhaust pipes burned or corroded?
ÐGo to Step 11Go to Step 12
11Replace the exhaust pipes, as required.
Is your action complete?
ÐGo to Step 2Ð

6E±243 ENGINE DRIVEABILITY AND EMISSIONS
DTC P1154 ± HO2S Transition Time Ratio Bank 2 Sensor 1

 
StepNo Ye s Value(s) Action
12Check for leaks at the exhaust manifold.
Are there leaks at the exhaust manifold?
ÐGo to Step 13Go to Step 14
13Tighten the bolts to specifications or replace the
manifold if necessary.
Is your action complete?
ÐGo to Step 2Ð
14Visually/physically inspect the following items:

Ensure that the Bank 2 HO2S 1 is securely
installed.

Check for corrosion on terminals.

Check terminal tension (at Bank 2 HO2S 1 and at
the PCM).

Check for damaged wiring.
Was a problem found in any of the above areas?
ÐGo to Step 18Go to Step 15
151. Disconnect Bank 1 HO2S 1.
2. Ignition ªON.º
3. Using a DVM at the PCM side of the HO2S 1
connector, measure the voltage between the high
signal circuit and ground.
Also measure the voltage between the low signal
circuit and ground.
Are both voltages in the specified range?
3-4 V
Go to Step
16
Go to Step 19
161. With Bank 1 HO2S 1 disconnected, jumper the high
and low (PCM side) signal circuits to ground.
2. Ignition ªON.º
3. Using Tech 2, monitor the Bank 2 HO2S 1 voltage.
Does the scan too indicate less than 10 mV and
immediately return to about 450 mV when the jumper is
removed?
ÐGo to Step 21Go to Step 22
17Replace affected heated oxygen sensors.
NOTE: Before replacing sensors, the cause of the
contamination must be determined and corrected.

Fuel contamination.

Use of improper RTV sealant.

Engine oil/coolant consumption.
Is the action complete?
ÐVerify repairÐ
18Repair condition as necessary.
Is the action complete?
ÐVerify repairÐ
19Check for faulty PCM connections or terminal damage.
Is the action complete?
ÐVerify repairGo to Step 20
20Repair open, short or grounded signal circuit.
Is the action complete?
ÐVerify repairÐ

6E±246
ENGINE DRIVEABILITY AND EMISSIONS
amounts of fuel at idle, but may not be able to supply
enough fuel during heavy acceleration.

Water or alcohol in the fuel may cause low HO2S
voltage during acceleration.

Check for faulty or plugged fuel injector(s).

Check for low fuel.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.4. When the engine is idling or at steady cruise, the
HO2S voltage should vary from between
approximately 100 mV to 900 mV. It is possible to
measure a satisfactory fuel pressure at idle even
though the pressure may drop at high flow
requirements. It may be necessary to watch fuel
pressure at high engine load.
5. Wrap a shop towel around the fuel pressure
connector to absorb any small amount of fuel
leakage that may occur when installing gauge.
Ignition ªON,º pump pressure should be 280-320
kPa.
DTC P1171 ± Fuel System Lean During Acceleration

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any component-related DTCs set?
Ð
Go to
component
DTC charts
Go to Step 3
31. Check the vehicle's fuel tank for an adequate
amount of fuel.
2. Add fuel to the vehicle's fuel tank if the tank is almost
empty.
Was fuel added to the vehicle's fuel tank?
ÐGo to Step 4Go to Step 5
41. Place the transmission in park.
2. Using Tech 2, observe HO2S 1 voltage while
running warm engine 75
C-95
C (167
F-203
F) at
1200 RPM.
3. HO2S 1 voltage should vary within the specified
range.
4. Quickly open the throttle halfway for a few seconds.
Did the voltage suddenly rise toward the high end of the
specified range?
100-900 mV
Go to Chart
A-7
Go to Step 5
51. Disconnect the fuel pump relay and crank the
engine to relieve the fuel pressure.
2. Install the fuel pressure gauge.
3. Start the engine and idle at normal operating
temperature.
4. Disconnect the vacuum line going to the fuel
pressure regulator.
With the engine running, is the fuel pressure within the
specified range?
280-325 kPa
(41-46 psi)
Go to OBD
System
Check
Go to Step 6
6Check for restricted fuel lines or restricted in-line filter.
Was a problem found?
ÐVerify repairGo to Step 7

6E±247 ENGINE DRIVEABILITY AND EMISSIONS
DTC P1171 ± Fuel System Lean During Acceleration

 
StepNo Ye s Value(s) Action
71. Ignition ªOFF.º
2. Remove the fuel pump relay and replace it with a
fused jumper which will connect the relay's battery
terminal to the terminal leading to the fuel pump
fuse.
3. While the fuel pump is operating, use pliers to slowly
close the return line (do not exceed the first
specified value).
Using the pliers to restrict the return line, can the fuel
pressure be manipulated to exceed the second
specified value?
414 kPa
(60 psi)
325 kPa
(46 psi)
Go to
Diagnostic
Aids
Go to Step 8
8Check for:

Faulty fuel pump

Restricted fuel pump strainer (sock)

Incorrect fuel pump

Incorrect fuel being used

Hot fuel
Is the action complete?
ÐVerify repairÐ

6E±248
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1380 ABS Rough Road ABS System Fault
Circuit Description
The powertrain control module (PCM) monitors ABS fault
signal. When PCM receives fault signal, PCM will set
DTC P1380.
Conditions for Setting the DTC

Vehicle speed is more than 5 mph.

Load is less than 99%.

Engine revolution is less than 6250 rpm.

PCM receives ABS fault signals from ABS unit.

Ignition on.

Misfire DTCs exist.

100 test failures within 120 test samples.
Action Taken When the DTC Sets

The PCM will store DTC 1380 only, no MIL turn on.
Conditions for Clearing the MIL/DTC

A history DTC P1380 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC 1380 can be cleared by using Tech-2 or
disconnecting the PCM battery feed.
Diagnostic Aids
Check for the following conditions:

PCM and ABS communication line short circuit to other
line may cause faulty signal. Inspect communication
line.

Follow ABS ECU diagnosis procedure, refer to ABS
procedure page.
DTC P1380 ± ABS Rough Road ABS System Fault

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 ªOFFº, 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
P1380 and Misfire DTCs until the DTC P1380 and
Misfire DTCs test runs. Note the result.
Does the Tech 2 indicates DTC P1380 and Misfire
DTCs failed this ignition?
Ð
Refer to ABS
diagnosis
After inspect
ABS, unit re-
peat
Step 2
Still problem
exists, go to
Step 3
Clear DTC by
Tech 2
3Check short circuit among communication line of
PCM/ABS and others.
Was short circuit?
Ð
Repair wiring
Verify repair
Go to Step 4
4Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±249 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1404 EGR Closed Stuck
D06RW106
Circuit Description
The powertrain control module (PCM) monitors the EGR
valve pintle position input to ensure that the valve
responds properly to commands from the PCM, and to
detect a fault if current pintle zero position is different from
the learned zero position. If the PCM detects a pintle
position signal indicates more than 30 % different
between current zero position and the learned zero
position and more than 5 seconds, and this condition
meet 3 times during trip, then the PCM will set DTC
P1404.
Conditions for Setting the DTC

Ignition voltage is between 11 and 16 volts.

Intake Air temp is more than 3
C.

Desire EGR position is 0.

Difference EGR pintle position between current and
the learned zero is more than 30 % last more than 5
seconds, and meet three time to the above condition
during a trip. Then it trigger the PCM lights on.
Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after consecutive 2nd 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 Failure
Records data.
Conditions for Clearing the MIL/DTC

DTC P1404 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:

Excessive carbon deposit on EGR valve shaft or/and
foreign material may cause no return to EGR valve
fully seated. Those carbon deposit may occur by
unusual port operation. Remove foreign material
or/and excessive carbon deposit on EGR valve shaft
may make return to EGR valve fully seated.

Poor connection or damaged harness ± Inspect the
wiring harness for damage. Same as P1406
description
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.

6E±250
ENGINE DRIVEABILITY AND EMISSIONS
DTC P1404 ± EGR Closed Stuck

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 ªOFFº, review and record
Tech 2 Failure Records Data.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor ªDTC inf. for DTC P1404
until the DTC P1404 test runs. Note the result.
Does the Tech 2 indicates DTC P1404 failed this
ignition?
ÐGo to Step 3
Refer to
Diagnostic
Aids
31. Disconnect the EGR valve harness connector.
2. Inspect the EGR valve and connectors for damaged
pin or terminals.
Were there any damaged pins or terminals?
ÐGo to Step 4Go to Step 5
4Repair the damaged pin or terminal.
Is the action complete?
ÐVerify repairÐ
51. Remove EGR valve from Engine.
2. Inspect EGR valve whether there is any excessive
carbon deposit on EGR shaft.
3. Inspect any foreign material inside of EGR valve.
Was excessive carbon deposit on EGR valve shaft
or/and foreign material in EGR valve ?
ÐGo to Step 6Go to Step 7
61. Clean up EGR valve shaft and inside of EGR valve.
2. Remove foreign material from EGR valve.
3. Visually inspect damage of pintle and seat whether
there is bent, leakage may occur.
Was there any severe damage which affects function?
3±6 ohmsGo to Step 8
Verify repair
Go to
Step 7
71. Reconnect.
2. Ignition ªOFFº.
3. Install the Tech 2.
4. Run the engine at idle.
5. On the Tech 2, select F3:Misc. Test F5:EGR.
6. Use the ªUPº arrow to increase the EGR from 0% to
40%.
Did EGR work properly?
ÐÐGo to Step 8
81. Reset the learned zero EGR valve position.
2. Repeat step 7.
Did EGR work properly?
ÐVerify repairGo to Step 9
9Replace the EGR valve.
Replace the EGR valve. Does DTC P1404 still fail
ªspecific DTCº test on the Tech 2?
ÐGo to Step 10Verify repair
10Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±251 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1508 IAC System Low RPM
T321115
Circuit Description
The powertrain control module (PCM) controls engine
idle speed by adjusting the position of the idle air control
(IAC) motor pintle. The IAC is a bi-directional stepper
motor driven by two coils. The PCM applies current to the
IAC coils in steps (counts) to extend the IAC pintle into a
passage in the throttle body to decrease air flow. The
PCM reverses the current to retract the pintle, increasing
air flow. This method allows highly accurate control of idle
speed and quick response to changes in engine load. If
the PCM detects a condition where too low of an idle
speed is present and the PCM is unable to adjust idle
speed by increasing the IAC counts, DTC P1508 will set,
indicating a problem with the idle control system.
Conditions for Setting the DTC

No Tech 2 test is being run.

None of these DTCs are set: TP sensor, VSS, ECT,
EGR, fuel system, MAF, MAP, IAT, canister purge,
injector control or ignition control.

Barometric pressure is above 75 kPa.

Engine coolant temperature (ECT) is above 50
C
(120
F).

Engine speed is more than 100-200 RPM lower than
desired idle, based upon coolant temperature.

The engine has been running for at least 125 seconds.

Vehicle speed is less than 1 mph.

Canister purge duty cycle is above 10%.

Ignition voltage is between 9.5 volts and 16.7 volts.
The throttle is closed.

Engine speed is lower than desired idle.

All of the above conditions are met for 10 seconds.
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.
Conditions for Clearing the MIL/DTC

DTC P1508 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 or IAC motor ± 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 for damage.

Restricted air intake system ± Check for a possible
collapsed air intake duct, restricted air filter element,
or foreign objects blocking the air intake system.

Throttle body ± Check for objects blocking the IAC
passage or throttle bore, excessive deposits in the IAC