1998 ISUZU TROOPER sensor

6E±165 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0174 ± Fuel Trim System Lean Bank 2

 
StepNo Ye s Value(s) Action
101. Visually and physically inspect the throttle body,
intake manifold, EGR valve and the EGR feed pipe
for vacuum leaks.
2. Repair any vacuum leaks as necessary.
Did your inspection reveal a vacuum leak?
ÐVerify repairGo to Step 11
11Check the fuel for excessive water, alcohol, or other
contaminants (see
Diagnosis in Engine Fuel for
procedure) and correct the contaminated fuel condition
is present (see
Engine Fuel).
Was the fuel contaminated?
ÐVerify repairGo to Step 12
121. Visually and physically inspect the PCM injector
grounds, power grounds and sensor grounds to
ensure that they are clean, tight, and in their proper
locations.
2. If a faulty ground condition is present, correct it as
necessary.
Did your inspection reveal a condition requiring repair?
ÐVerify repairGo to Step 13
131. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in ªclosed loopº while
monitoring the ªBANK 1 S.T. FUEL TRIMº displayed
on the Tech 2.
Does the ªBANK 1 S.T. FUEL TRIMº value decrease to
near the specified value?
0%Go to Step 19Go to Step 14
14Perform the procedure in the ºFuel System Pressure
Testº and repair fuel system problem if necessary.
Did the Fuel System Pressure Test isolate a condition
requiring repair?
ÐVerify repairGo to Step 15
151. Visually and physically inspect the intake manifold,
injector O-rings, EGR adapter, EGR valve and the
EGR feed pipes for vacuum leaks.
2. Repair any problem that is found.
Did your inspection reveal a problem?
ÐVerify repairGo to Step 16
16Visually and physically inspect the Bank 2 exhaust
manifold for leaks and loose or missing hardware and
correct any problem found.
Did your inspection reveal a problem?
ÐVerify repairGo to Step 17
17Perform the ªInjector Balance Test,º and correct any
problem found (refer to
Fuel Metering System).
Did the Injector Balance Test isolate a problem?
ÐVerify repair Go to Step 18
181. Visually and physically inspect the Bank 2 HO2S 1
to ensure that it is installed securely and that the
Bank 2 HO2S 1 pigtail and wiring harness are not
contacting the exhaust or otherwise damaged.
2. If a problem is found, correct it as necessary.
Did your inspection reveal a problem?
ÐVerify repair
Refer to
Diagnostic
Aids
19Replace the MAF sensor.
Is the action complete?
ÐVerify repairÐ

6E±168
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0175 ± Fuel Trim System Rich Bank 2

StepActionValue(s)Ye sNo
1Was the ºOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Are any DTCs set other than P0172 and P0175?
Ð
Go to the
applicable
DTC charts
and repair the
other DTCs
before
proceeding
with this
chart.
Go to Step 3
31. Start the engine and operate the vehicle in ªclosed
loop.º
2. Observe the ªBANK 2 L.T. FUEL TRIMº display on
the Tech 2.
Is the displayed value more negative than the specified
value?
L.T. Fuel
Trim: ±15%
(auto. trans.)
OR ±12%
(man. trans.)
Go to Step 5Go to Step 4
41. Review and record the Tech 2 Failure Records data.
2. Clear the DTC P0172/P0175 and operate the
vehicle to duplicate the Failure Records conditions.
3. Monitor the Tech 2 ªDTCº info for DTC P0175 while
operating the vehicle to duplicate the Failure
Records conditions.
4. Continue operating the vehicle until the DTC P0175
test runs.
5. Note the test result.
Does the Tech 2 indicate DTC P0175 failed this
ignition?
ÐGo to Step 5
The rich
condition is
not present.
If a
driveability
symptom still
exists, refer
to
Symptoms.
5Was DTC P0172 also set?ÐGo to Step 6Go to Step 15
6Visually and physically inspect the air filter element and
replace it if necessary.
Did the air filter require replacement?
ÐVerify repairGo to Step 7
7Visually and physically inspect the air intake duct for
collapse or restriction and repair if necessary.
Did your inspection reveal a problem requiring repair?
ÐVerify repairGo to Step 8
8Inspect the MAF sensor inlet screen for damage or for
the presence of foreign objects which may partially
block air flow through the screen and correct any
problem found.
Did your inspection of the MAF sensor reveal a
condition requiring repair or replacement?
ÐVerify repairGo to Step 9
9Start the engine and note the idle quality.
Is a low or unsteady idle being experienced?
ÐGo to Step 10Go to Step 11
101. Turn the ignition off and physically inspect the
throttle body bore, throttle plate, and IAC passages
for coking and foreign objects.
2. If a problem was found, repair as necessary.
Did your inspection reveal a condition requiring repair?
ÐVerify repairGo to Step 11

6E±169 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0175 ± Fuel Trim System Rich Bank 2

 
StepNo Ye s Value(s) Action
111. Disconnect the vacuum hose from the fuel pressure
regulator and inspect the hose for the presence of
fuel.
2. If fuel is present in the vacuum hose, replace the
fuel pressure regulator (refer to
Fuel Metering
System
).
Did the fuel pressure regulator require replacement?
ÐVerify repairGo to Step 12
121. Ignition ªON,º engine ªOFF.º
2. Monitor the TP Angle display on the Tech 2 while
slowly depressing the accelerator pedal.
Does the TP Angle display increase steadily and
evenly from minimum value at closed throttle to
maximum value at wide-open throttle?
Minimum 0%
Maximum
100%
Go to Step 13Go to Step 18
131. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in ªclosed loopº while
monitoring the ªBANK 1 L.T. FUEL TRIMº and
ªBANK 1 S.T. FUEL TRIMº display on the Tech 2.
Did both values change to near the specified value?
0%Go to Step 19Go to Step 14
141. Perform the ªFuel System Pressure Test.º
2. If Fuel System Pressure Test isolates a problem,
repair as necessary (refer to
Engine Fuel or Fuel
Metering System
).
Did the Fuel System Pressure Test isolate a condition
requiring repair?
ÐVerify repairGo to Step 16
15Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ
161. Perform the ªInjector Balance Test.º
2. If the Injector Balance Test isolates a problem,
repair as necessary (refer to
Fuel Metering
System
).
Did the Injector Balance Test isolate a problem
requiring repair?
ÐVerify repairGo to Step 17
171. Remove and visually/physically inspect the Bank 2
HO2S 1 for silicon contamination. This will be
indicated by a powdery white deposit on the portion
of the HO2S that is exposed to the exhaust stream.
2. If contamination is evident on the Bank 2 HO2S 1,
replace the contaminated sensor.
Did the sensor require replacement?
ÐVerify repair
Refer to
Diagnostic
Aids
181. Check the TP sensor mounting screws and tighten
or replace them as necessary if they are loose or
missing.
2. If the screws are OK, replace the TP sensor.
Is the action complete?
ÐVerify repairÐ
19Replace the MAF sensor.
Is the action complete?
ÐVerify repairÐ

6E±188
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0325 KS Module Circuit
D06RW035
Circuit Description
The knock sensor is used to detect engine detonation,
allowing the powertrain control module (PCM) to retard
ignition control (IC) spark timing based on the knock
sensor (KS) signal being received. The knock sensor
produces an AC signal so that under a no knock condition
the signal on the KS circuit measures about 0.007 V AC.
The KS signal's amplitude and frequency depend upon
the amount of knock being experienced. The PCM
contains a non-replaceable knock filter module called a
signal-to-noise enhancement filter (SNEF) module. This
filter module in the PCM determines whether knock is
occurring by comparing the signal level on the KS circuit
with the voltage level on the noise channel. The noise
channel allows the PCM to reject any false knock signal
by knowing the amount of normal engine mechanical
noise present. Normal engine noise varies depending on
engine speed and load. When the PCM determines that
an abnormally low noise channel voltage level is being
experienced, a DTC P0325 will set.
Conditions for Setting the DTC

Engine has been running for at least 30 seconds.

The PCM determines that its internal signal from its
knock filter module indicates a continuous knocking
condition for more than 10 seconds.
Action Taken When the DTC Sets

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 ªsubstituteº default spark retard
value of 6 degrees to minimize knock during conditions
when knock is likely to occur.
Conditions for Clearing the MIL/DTC

DTC P0325 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
Check for the following conditions:

Poor connection at PCM ± Inspect the knock sensor
and PCM connectors for backed-out terminals, broken
locks, and improperly formed or damaged terminals.

Misrouted harness ± Inspect the knock sensor harness
to ensure that it is not routed too close to high voltage
wires such as spark plug leads.
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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Ensures that the fault is present.

6E±190
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0327 KS Sensor Circuit
D06RW035
Circuit Description
The powertrain control module (PCM) uses the knock
sensor to detect engine detonation, allowing the PCM to
retard ignition control (IC) spark timing based on the
knock sensor (KS) signal being received. The knock
sensor produces an AC signal so that under a no knock
condition the signal on the KS circuit measures about
0.007 V AC. The signal amplitude and frequency are
dependent upon the amount of knock being experienced.
The PCM monitors the KS signal and can diagnose the
KS sensor and circuitry.
Conditions for Setting the DTC

Engine running for at least 10 seconds.

The TP sensor is greater than 5%.

The ECT sensor is greater than 60
C (140
F).

Engine speed is between 2000 and 4000 RPM.

The knock sensor signal voltage is less than 0.20 volts,
or greater than 4.8 volts.

All conditions are present for more than 15 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.

The PCM will use a calculated spark retard value to
minimize knock during conditions when knock is likely
to occur. The calculated value will vary based on
engine speed and load.
Conditions for Clearing the MIL/DTC

DTC P0327 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Ensures that the fault is present.
4. The knock sensor is attached to a short jumper
harness, so it can be tested without removing the
intake manifold. A 2-wire connector for the knock
sensor is accessible behind the left rear fuel injector.

6E±191 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0327 ± KS Sensor Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2IMPORTANT:If an engine knock can be heard, repair
the engine mechanical problem before proceeding with
this diagnostic.
1. Operate the engine within the conditions specified
in diagnostic support ªConditions for Setting the
DTC.º
2. Using Tech 2, monitor ªSpecific DTCº info for DTC
P0327 until the DTC P0327 test runs.
3. Note the test result.
Does Tech 2 indicate DTC P0327 failed this ignition?
ÐGo 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.
4. Using Tech 2, monitor ªSpecific DTCº info for DTC
P0327 until the DTC P0327 test runs.
5. Note the test result.
Does Tech 2 indicate DTC P0327 failed this ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Check for a damaged terminal at the knock sensor
connector.
2. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
5Using a test light to battery +, check the black/blue wire
(PCM side) to verify that the shield connection is good.
Did the test light illuminate?
ÐGo to Step 7Go to Step 6
6Repair the open shield ground.
Is the action complete?
ÐVerify repairÐ
71. Ignition ªOFF,º disconnect the PCM.
2. Check the KS signal circuit for a poor terminal
connection at the PCM.
3. If a problem is found, replace the faulty terminal.
Was a problem found?
ÐVerify repairGo to Step 8
81. Ignition ªOFF,º PCM disconnected.
2. Check the KS signal circuit between the PCM and
the knock sensor connector for an open, a short to
voltage, or a short to ground.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 9
91. Ignition ªOFF,º PCM disconnected.
2. Knock sensor connected.
3. Measure the resistance of the knock sensor by
connecting the DVM between the PCM connector
and the engine block.
Is the resistance of each knock sensor near the
specified value?
100K ohmsGo to Step 10Go to Step 11

6E±192
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0327 ± KS Sensor Circuit

 
StepNo Ye s Value(s) Action
101. Ignition ªOFF,º PCM disconnected.
2. Connect the DVM to monitor AC voltage between
the PCM connector and engine ground.
3. Tap on the engine lift bracket with a socket
extension while observing the signal indicated on
the DVM.
Is any signal indicated on the DVM while tapping on the
engine lift bracket?
ÐGo to Step 12Go to Step 11
11Replace the knock sensor.
Is the action complete?
ÐVerify repairÐ
12Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±193 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0336 58X Reference Signal Circuit
D06RW032
Circuit Description
The 58X reference signal is produced by the crankshaft
position (CKP) sensor. During one crankshaft revolution,
58 crankshaft pulses will be produced. The powertrain
control module (PCM) uses the 58X reference signal to
calculate engine RPM and crankshaft position. The PCM
constantly monitors the number of pulses on the 58X
reference circuit and compares them to the number of
camshaft position (CMP) signal pulses being received. If
the PCM receives an incorrect number of pulses on the
58X reference circuit, DTC P0336 will set.
Conditions for Setting the DTC

Engine is running.

Extra or missing pulse is detected between
consecutive 58X reference pulses.

Above condition is detected in 10 of 100 crankshaft
rotations.
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 P0336 can be cleared by using Tech 2 ªClear Infoº
function or by disconnecting the PCM battery feed.
Diagnostic Aids
An intermittent may be caused by a poor connection,
rubbed-through wire insulation or a wire broken inside the
insulation. Check for:

Poor connection - Inspect the PCM harness and
connectors for improper mating, broken locks,
improperly formed or damaged terminals, and poor
terminal-to-wire connection.