Toyota Celica 2005 Repair Manual page 373

DI−174
DTC P0325
CIRCUIT DESCRIPTION
The knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelec-
tric element which generates a voltage when it becomes deformed, which occurs when the cylinder block
vibrates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.
DTC No.
No knock sensor 1 signal to ECM with engine speed, 2,000
P0325
rpm or more
HINT:
If the ECM detects above diagnosis conditions, it operates the fail safe function in which the corrective retard
angle value is set to the maximum value.
KNK signal waveform
0.5V/
Division
0V
5 m sec./Division
0.5V/
Division
0V
100 sec./Division
2005 CELICA (RM1131U)
DIAGNOSTICS
Knock Sensor 1 Circuit (Bank 1 or Single
Sensor)
DTC Detecting Condition
Reference: INSPECTION USING OSCILLOSCOPE
S
HINT:
The correct waveforms are as shown.
S
HINT:
If normal mode vibration frequency is not 7.6 kHz the sensor is
malfunctioning.
A00406
− ENGINE (1ZZ−FE)
S Open or short in knock sensor 1 circuit
S Knock sensor 1 (looseness)
S ECM
With the engine racing (4,000 rpm), measure between
terminal KNK of the ECM connector and body ground.
Spread the time on the horizontal axis, and confirm that
period of the wave is 80 μ sec.
(Normal mode vibration frequency of knock sensor:
12.5 kHz
372
Trouble Area
DI38A−15