Isuzu Rodeo UE. Manual — part 210
6E1–211
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0325 KNOCK SENSOR (KS) CIRCUIT
MALFUNCTION
D06RX051
Circuit Description
The knock sensor (KS) system is used to detect engine
detonation. The knock sensor produced an AC voltage
signal. The knock sensor sends this signal to the PCM.
The amplitude and the frequency of the AC voltage signal
depends upon the knock level being detected. The PCM
will then retard the spark timing based on the signals from
the Knock Sensor. DTC P0325 is a type B code.
Conditions for Setting the DTC
f
Engine run time is greater than 10 seconds.
f
No P0327 Diagnostic Trouble Code set.
f
Engine speed is above 2500 rpm.
All the above mentioned conditions are met, and the
following conditions are met for 8.75 seconds within a 10
second monitoring period:
f
Any of the four A/D voltages exceeds 1.5625 Volts.
f
Instantaneous A/D delta Voltage falls below 0.019531
Volts.
Action Taken When the DTC Sets
f
The Malfunction Indicator Lamp (MIL) will illuminate
the second time the fault is detected.
f
The PCM will record operating conditions at the time
the diagnostic fails.
f
A history Diagnostic Trouble Code is stored.
f
The PCM will use a calculated spark retard value in
order to minimize the knock during the conditions when
the knock is likely to occur. The calculated value will
vary based on the engine speed and load.
Conditions for Clearing the MIL/DTC
f
The MIL will turn off after 3 consecutive ignition cycles
in which the diagnostic runs without a fault.
f
A history Diagnostic Trouble Code will clear after 40
consecutive warm up cycles without a fault.
f
A Tech 2 can clear the Diagnostic Trouble Codes.
Diagnostic Aids
Correct any abnormal engine noise before using the
diagnostic table.
Check for an open ignition feed circuit.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
1. The Powertrain OBD System Check prompts the
technician to complete some basic checks and store
the freeze frame data and failure records data on
the Tech 2 if applicable. This creates an electronic
copy of the data taken when the malfunction
occurred. The information is then stored on the
Tech 2 for later reference.
6E1–212
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
2. If the conditions for the test as described above are
met, a Diagnostic Trouble Code P0325 will set and
MIL will illuminate.
4. If the engine has an internal knock or audible noise
that causes a knocking type noise on the engine
block, the knock sensor may be responding to the
noise.
6. The Tech 2 displays knock sensor activity in counts,
approximately 20–50 at idle. The counts should
increase when engine speed is increased and the
counts should decrease when engine speed is
decreased.
7. Any circuitry, that is suspected as causing the
complaint, should be thoroughly checked for backed
out terminals, improper mating, broken locks,
improperly formed or damaged terminals, poor
terminal to wiring connections or physical damage
to the wiring harness.
8. If the KS module was previously replaced and the
Diagnostic Trouble Code resets, a malfunctioning
PCM is indicated.
NOTE: Replacement PCMs must be reprogrammed.
Refer to On–Vehicle Service in Powertrain Control
Module and Sensors for procedures.
9. Checking the internal resistance of the knock sensor
verifies if the knock sensor or the wiring to the
knock sensor is OK.
DTC P0325 KS Circuit Malfunction
Step
Action
Value(s)
Yes
No
1
Was the Powertrain ”On–Board Diagnostic (OBD)
System Check” performed?
—
—
Go to Step 2
Go to
Powertrain
OBD System
Check
2
1. Start the engine.
2. Install a Tech 2.
3. Clear the Diagnostic Trouble Codes.
4. Run the engine at slightly more than 10% throttle
angle.
Does the Malfunction Indicator Lamp (MIL) illuminate?
—
Go to Step 4
Go to Step 3
3
1. Turn the ignition switch ON, with engine OFF.
2. Review the Freeze Frame data and note the
parameters.
3. Operate the vehicle within the Conditions and
Conditions for Setting the DTC as noted.
Does the Malfunction Indicator Lamp (MIL) illuminate?
—
Go to Step 4
Go to Step
13
4
Listen to the engine while raising and lowering the
engine speed.
Is a knock or audible noise present?
—
Go to Step 5
Go to Step 6
5
Repair the mechanical engine problem or a loose
bracket or component.
Is the action complete?
—
Go to Step
13
—
6
Slowly increase the engine speed to the specified
value.
Does the KS Activity increase with the engine speed?
2500 RPM
Go to Step 7
Go to Step
11
7
Check for a poor connection at the PCM connector,
Knock sensor signal circuit and repair as necessary.
Was a repair necessary?
—
Go to Step
13
Go to Step 8
6E1–213
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DTC P0325 KS Circuit Malfunction
(Cont'd)
Step
No
Yes
Value(s)
Action
8
Replace the PCM.
IMPORTANT: The replacement PCM must be
programmed. Refer to On–Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
—
Go to Step
13
—
9
1. Turn the ignition switch OFF.
2. Disconnect the PCM connectors at the PCM.
3. With a Digital Voltmeter (DVM) connected to
ground, measure the resistance of the knock
sensor through the knock sensor signal circuit.
Is the measured value within the specified value?
90K – 110K
W
Go to Step 7
Go to Step
10
10
Check the knock sensor electrical connector for a poor
connection and repair as necessary.
Was a repair necessary?
—
Go to Step
13
Go to Step
11
11
Check the knock sensor signal circuit for an open or a
short to ground or to voltage and repair as necessary.
Was a repair necessary?
—
Go to Step
13
Go to Step
12
12
Replace the Knock Sensor (KS).
Is the action complete?
—
Go to Step
13
—
13
1. Using the Tech 2, clear the Diagnostic Trouble
Codes.
2. Start the engine and idle at normal operating
temperature.
3. Operate the vehicle within the conditions for setting
this Diagnostic Trouble Code as specified in the
supporting text.
Does the Tech 2 indicate that this diagnostic has ran
and passed?
—
Go to Step
14
Go to Step 2
14
Check is any additional Diagnostic Trouble Codes are
set.
Are any Diagnostic Trouble Codes displayed that have
not been diagnosed?
—
Go to
applicable
DTC table
System OK
6E1–214
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0327 KNOCK SENSOR (KS) CIRCUIT
LOW INPUT
D06RX051
Circuit Description
The PCM uses the Knock Sensor (KS) in order to detect
engine detonation. This allows the PCM to retard the
Ignition Control (IC) spark timing based on the KS signal
the PCM receives. The circuitry within the knock sensor
pulls down the PCM–supplied 5 volt signal, so that under
a no knock condition the signal on the KS circuit
measures about 1.3 volts. The knock sensors produce an
AC signal that rides on the 1.3 volts DC. The signal’s
amplitude and frequency are dependent upon the amount
of the knock being experienced.
The PCM determines whether the knock is occurring by
comparing the signal level on the KS circuit with a voltage
level on the noise channel. The noise channel allows the
CM to reject any false knock signal by indicating the
amount of normal engine mechanical noise present. The
normal engine noise varies depending on the engine
speed and load. Then the ECM determines that an
abnormally high noise channel voltage level is being
experienced, a Diagnostic Trouble Code P0327 sets.
This DTC is a type B DTC.
Conditions for Setting the DTC
A/D Test
The following conditions are met for 7.5 seconds within a
10 second monitoring period:
f
Engine speed is equal to or greater than 2000 RPM.
f
A/D Voltage is less than or equal to 0.0977 Volts.
Gain Test
The following conditions are met for 7.5 seconds within a
10 second monitoring period:
f
Engine speed is greater than 2500 RPM.
f
Gain is equal to or greater than 23.875 dB.
Action Taken When the DTC Sets
f
The PCM will illuminate the MIL the second time the
fault is detected.
f
The PCM will store the conditions which were present
then the Diagnostic Trouble Code set.
f
The PCM will use a calculated spark retard value in
order to minimize the knock during the conditions when
the knock is likely to occur. The calculated value will
vary based on the engine speed and load.
Conditions for Clearing the MIL/DTC
f
A history Diagnostic Trouble Code will clear after 40
consecutive warm–up cycles have occurred without a
fault.
f
The Tech 2 ”Clear Info” will clear the Diagnostic Trouble
Code.
Diagnostic Aids
Check for the following conditions:
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