DTC 53

DTC 53 Knock Sensor CPU Malfunction

CIRCUIT DESCRIPTION
Knock sensors are fitted one each to the front and rear of the left side of the cylinder block to detect engine knocking. This sensor contains a piezoelectric 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.





DETECTING CONDITION
If the ECM detects the above diagnosis conditions, it operates the fail safe function in which the corrective retard angle value is set to the maximum value.

DIAGNOSTIC TROUBLE CODE DETECTION DRIVING PATTERN

Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is recorded.
(b) To check that the malfunction is corrected when the repair is completed by confirming that diagnostic trouble code is no longer detected.

Driving Pattern Detection:

Malfunction: Open or Short in Knock Sensor

(1) Start the engine and warm up.
(2) Idle the engine for 3 min.
(3) With the A/C ON, race the engine quickly to 5,000 rpm 3 times. (Rapidly depress the accelerator pedal and suddenly release it.)

HINT: If a malfunction exists, the malfunction indicator lamp will light up when sudden racing is performed.

NOTICE: If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.





WIRING DIAGRAM

Step 1:

Step 2:

Step 3:

Step 4:

INSPECTION PROCEDURE

HINT:
If diagnostic trouble code 52 is displayed, check No.1 knock sensor (for front side) circuit.
If diagnostic trouble code 55 is displayed, check No.2 knock sensor (for rear side) circuit.
If diagnostic trouble code 53 is displayed, replace engine control module.

Reference INSPECTION USING OSCILLOSCOPE
- With the engine racing (4,000 rpm) measure waveform between terminals KNK1, KNK2 of engine control module and body ground.





HINT: The correct waveform is as shown.

- Spread the time on the horizontal axis, and confirm that the period of the wave is 123 micro sec. (Normal mode vibration frequency of knock - sensor: 8.1 KHz).





HINT: If normal mode vibration frequency is not 8.1 KHz, the sensor is malfunctioning.