Diagnostic Trouble Code (Dtc) P0327 Knock Sensor (Ks) Circuit Low Input - Isuzu 1999 RODEO Workshop Manual

6E1–214 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0327 KNOCK SENSOR (KS) CIRCUIT
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.
LOW INPUT
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:
D06RX051