1998 ISUZU TROOPER check engine

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±189 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0325 ± KS Module 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 vehicle within parameters specified
under criteria included in ªConditions for Setting the
DTC.º
2. Using Tech 2, monitor ªSpecific DTCº info for DTC
P0325 until the DTC P0325 test runs.
3. Note the test result.
Does Tech 2 indicate DTC P0325 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 for
DTC P0325.
3. Operate the vehicle within Failure Records
conditions.
4. Using Tech 2, monitor ªSpecific DTCº info for DTC
P0325 until the DTC P0325 test runs.
Does Tech 2 indicate DTC P0325 test failed this
ignition?
ÐGo to Step 4
Refer to
Diagnostic
Aids
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±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±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.

6E±194
ENGINE DRIVEABILITY AND EMISSIONS

Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, disconnect
the PCM, turn the ignition on and observe a voltmeter
connected to the 58X reference circuit at the PCM
harness connector while moving connectors and
wiring harnesses related to the ICM. A change in
voltage will indicate the location of the fault.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 P0336 ± 58X Reference Signal Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Attempt to start the engine.
Does the engine start?
ÐGo to Step 3
Go to ªEngine
Cranks But
Will Not Runº
chart
31. Review and record Failure Records information.
2. Clear DTC P0336.
3. Start the engine and idle for 1 minute.
4. Observe DTCs.
Is DTC P0336 set?
ÐGo to Step 4
Refer to
Diagnostic
Aids
41. Disconnect the PCM and CKP sensor.
2. Check for an open or a short to ground in the 58X
reference circuit between the CKP sensor
connector and the PCM harness connector.
3. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 5
51. Reconnect the PCM and CKP sensor.
2. Connect a DVM to measure voltage on the 58X
reference circuit at the PCM connector.
3. Observe the voltage while cranking the engine.
Is the voltage near the specified value?
2.5 VGo to Step 8Go to Step 6
6Check the connections at the CKP sensor and replace
the terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 7
7Replace the CKP sensor. Use caution to avoid any hot
oil that may drip out.
Is the action complete?
ÐVerify repairÐ
8Check connections at the PCM and replace the
terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 9
9Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ

6E±195 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0337 CKP Sensor Circuit Low Frequency
D06RW032
Circuit Description
The 58X reference signal is produced by the crankshaft
position (CKP) sensor. During one crankshaft revolution,
58 crankshaft reference 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 does not receive pulses on the 58X
reference circuit, DTC P0337 will set.
Conditions for Setting the DTC

No camshaft position (CMP) sensor DTCs are set.

Engine cranking.

Crankshaft position (CKP) sensor signal is not present
between two cam pulses.

CKP reference pulse is not detected within 8 CMP
pulses.
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 P0337 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.

6E±196
ENGINE DRIVEABILITY AND EMISSIONS

Damaged harness ± Inspect the wiring harness for
damage. If the harness appears to be OK, disconnect
the PCM, turn the ignition on and observe a voltmeter
connected to the 58X reference circuit at the PCM
harness connector while moving connectors and
wiring harnesses related to the ICM. A change in
voltage will indicate the location of the fault.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 P0337 ± CKP Sensor Circuit Low Frequency

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Attempt to start the engine.
Does the engine start?
ÐGo to Step 3Go to Chart 3
31. Review and record Failure Records information.
2. Clear DTC P0337.
3. Start the engine and idle for 1 minute.
4. Observe DTCs.
Is DTC P0337 set?
ÐGo to Step 4
Refer to
Diagnostic
Aid
41. Disconnect the CKP sensor.
2. Ignition ªON.º
3. Using a DVM, verify that 5 V reference and ground
are being supplied at the sensor connector (PCM
side).
Are 4-6 volts and ground available at the sensor?
ÐGo to Step 7Go to Step 5
51. Ignition ªON.º
2. With a DVM, backprobe the PCM connector 5 V
reference and ground connections.
Are 5 V reference and ground available at the PCM?
ÐGo to Step 6Go to Step 11
6Check 5 V reference or ground between the CKP
sensor and PCM and repair the open circuit, short to
ground or short to voltage.
Is the action complete?
ÐVerify repairÐ
71. Ignition ªOFF.º
2. Disconnect the PCM and CKP sensor.
3. Check for an open or a short to ground in the 58X
reference circuit between the CKP sensor
connector and the PCM harness connector.
4. If a problem is found, repair as necessary.
Was a problem found?
ÐVerify repairGo to Step 8
81. Reconnect the PCM and CKP sensor.
2. Connect a DVM to measure voltage on the 58X
reference circuit at the PCM connector.
3. Observe the voltage while cranking the engine.
Is the voltage near the specified value?
2.5 VGo to Step 11Go to Step 9
9Check the connections at the CKP sensor and replace
the terminals if necessary.
Did any terminals require replacement?
ÐVerify repairGo to Step 10
10Replace the CKP sensor. Use caution and avoid hot oil
that may drip out.
Is the action complete?
ÐVerify repairÐ

6E±197 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0337 ± CKP Sensor Circuit Low Frequency

 
StepNo Ye s Value(s) Action
11Check the connections at the PCM and replace the
terminals if necessary.
Did any terminals require replacement?
ÐVerify repair Go to Step 12
12Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?ÐVerify repairÐ