Diag. Code 52 Knock Sensor Signal
CIRCUIT DESCRIPTION
The knock sensor is located on the cylinder block.
If knocking develops in the engine, the knock sensor, by resonating with the knocking vibration,
generates a voltage which corresponds to the knocking strength and sends a signal to the ECU.
Code No.
Diagnosis Trouble Area
52
With engine speed between 1,600
rpm–5,200 rpm, Signal from knock
sensor is not input to ECU for
Revolution. (KNK)
D Open or short in knock sensor circuit.
D Knock sensor (looseness etc.)
D ECU
DIAGNOSIS CODE DETECTION DRIVING PATTERN
Purpose of the driving patten.
(a) After the diag. code is erased, the malfunction is reproduced and the diag. code is recorded again.
(b) To check that the malfunction is cleared once the repair is completed (confirm that diag. code is no
longer detected).
Malfunction: Open or Short in Knock Sensor
À Start engine and warm engine up.
Á After engine is warmed up, let it idle for 3 min.
 With the A/C ON, perform sudden racing (5,000 rpm) three times.
(Rapidly depress the accelerator pedal and suddenly release it.)
HINT: If a malfunction exists, the ”CHECK” engine warning light will light up when
sudden racing is performed.
NOTICE: If the conditions in this test are not strictly observed, detection of the
malfunction will not be possible.
–ENGINE TROUBLESHOOTING Circuit Inspection
TR–71
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