ISUZU TROOPER 1998 Service Repair Manual

6E±184
ENGINE DRIVEABILITY AND EMISSIONS
DTC P0205 ± Injector 5 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 5 (green with black
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/black 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

6E±185 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0206 Injector 6 Control Circuit
D06RW034
Circuit Description
The powertrain control module (PCM) has six individual
injector driver circuits. Each controls an injector. When
the driver circuit is grounded by the PCM, the injector is
activated. The PCM monitors the current in each driver
circuit. The voltage on each driver is monitored to detect
a fault. If the voltage is not what the PCM expects to
monitor on the circuit, a DTC is set. This DTC is also set if
an injector driver is shorted to voltage or if there is an open
circuit.
Conditions for Setting the DTC

The battery voltage is more than 9 volts.

The engine is turning, determined by 58X crankshaft
position input signal.

The injector voltage does not equal the ignition voltage
when the injector is commanded ªOFFº or the injector
voltage does not equal 0 volts when the injector is
commanded ªON.º

The above conditions are met for 15 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.
Conditions for Clearing the MIL/DTC

DTC P0206 can be cleared by using the Tech 2 ªClear
Infoº function or by disconnecting the PCM battery
feed.
Diagnostic Aids
An injector driver circuit that is open or shorted to voltage
will cause a DTC P0206 to set. It will also cause a misfire
due to an inoperative injector. A misfire DTC will also be
set indicating which cylinder is inoperative.
Long term and short term fuel trims that are excessively
high or low are a good indication that an injector is faulty.
Use Fuel Injector Coil Test Procedure to check for faulty
injectors.
Test Description
The number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. This step determines if DTC P0206 is the result of a
hard failure or an intermittent condition.
5. A special injector test connector is provided so that
the injectors can be electrically tested without
removal of the manifold. On the Trooper, the
special 7-way gray connector is located at the front
of the charcoal canister. The test connector can be
identified by the blue connector lock which is
tethered to the wiring harness. If the light for
cylinder 6 is ªONº steady before cranking the engine
as well as while cranking the engine, then the
injector driver circuit is shorted to ground.

6E±186
ENGINE DRIVEABILITY AND EMISSIONS
If the test light blinks while cranking, the PCM and
the wiring to the injectors are OK. The Fuel Injector
Coil Test Procedure will check if the injectors are
faulty.
R321059
7. Because the test light was ªONº steady, voltage to
the injector is OK, but the driver circuit is grounded
at all times. This step determines if the circuit is
shorted to ground or the PCM is faulty.
9. The reading should be about 12-14
.
10.Locating the open in the harness or in the injector
will require removal of the manifold to provide
access.
DTC P0206 ± Injector 6 Control Circuit

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
2Will the engine start?
ÐGo to Step 3
Go to Engine
Cranks But
Will Not Run
chart
31. Install the Tech 2. Clear the DTC.
2. Idle the engine for one minute.
Does DTC P0206 reset?
ÐGo to Step 5Go to Step 4
41. Review the Freeze Frame data with the ignition
ªONº and the engine ªOFFº and note the
parameters.
2. Operate the vehicle within the Freeze Frame
conditions as noted.
Does P0206 reset?
ÐGo to Step 5
Go to
Diagnostic
Aids
51. Engine ªOFF.º
2. Disconnect the injector test connector.
3. Install an injector test light 5-8840-2636-0 on
injector connector.
4. Crank the engine and note the light.
Does the cylinder 6 test light blink?
Ð
Go to Fuel
Injector Coil
Test
Procedure
Go to Step 6
6Note whether the injector test light for cylinder 6 was
ªOFFº or ªONº steady in step 5.
Was the test light ªONº steady while cranking the
engine?
ÐGo to Step 7Go to Step 9

6E±187 ENGINE DRIVEABILITY AND EMISSIONS
DTC P0206 ± Injector 6 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 6 (green with yellow
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/yellow 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

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±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.