Toyota Celica 2005 Repair Manual page 671

DI−472
DTC P0327
DTC P0328
CIRCUIT DESCRIPTION
The flat type knock sensor (non−resonant type) has a structure that can detect vibrations in a wide frequency,
from about 6 kHz to 15 kHz, and has the following features.
Knock sensors are fitted to the right bank and left bank of the cylinder block to detect the engine knocking.
Each sensor contains a piezoelectric element which generates a voltage when it becomes deformed. This
occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, the ignition timing is
retarded to suppress it.
DTC No.
P0327 Output voltage of the knock sensor is 0.5 V or less
P0328 Output voltage of the knock sensor is 4.5 V or more
HINT:
If the ECM detects the DTC P0327 and P0328, it enters the fail−safe mode in which the corrective retarded
angle value is set to the maximum value.
KNK1 Signal Waveform
1 msec./ Division
MONITOR DESCRIPTION
The knock sensor located on the cylinder block detects spark knock.
When spark knock occurs, the sensor pick−up vibrates in a specific frequency range. When the ECM detects
the voltage in this frequency range, it retards the ignition timing to suppress the knock.
The ECM also senses background engine noise with the knock sensor and uses this noise to check for faults
in the sensor. If the knock sensor signal level is too low for more than 10 sec. and if the knock sensor output
voltage is out of the normal range, the ECM interprets this as a fault in the knock sensor and sets a DTC.
2005 CELICA (RM1131U)
DIAGNOSTICS
Knock Sensor 1 Circuit Low Input (Bank 1 or
Single Sensor)
Knock Sensor 1 Circuit High Input (Bank 1
or Single Sensor)
DTC Detecting Condition
Reference: Inspection by using the oscilloscope.
1V/ DIV
GND
A21262
− ENGINE (2ZZ−GE)
S Short in knock sensor circuit
S Knock sensor (under−torqued or loose)
S ECM
S Open in knock sensor circuit
S Knock sensor (under−torqued or loose)
S ECM
After warning up, run the engine at 4,000 rpm, and check
the waveform between terminals KNK1 and EKNK of the
ECM connector.
670
Trouble Area
DID5A−01