Inspection Procedure

DTC 52 - Knock Sensor Signal

PROCEDURE



1. CHECK CONTINUITY BETWEEN TERMINAL KNK OF ECM CONNECTOR AND BODY GROUND.
- Remove glove compartment.
- Disconnect the ECM connector.



- Measure resistance between terminal KNK of ECM connector and body ground.

Resistance: 1 M Ohm or higher

- If OK proceed to step 3.
- If not OK proceed to step 2.

2. CHECK KNOCK SENSOR.
- Disconnect knock sensor connector.



- Measure resistance between the knock sensor terminal and body.

Resistance: 1 M Ohm or higher

- If OK proceed to step 3.
- If not OK replace knock sensor

3. CHECK FOR OPEN AND SHORT IN HARNESS AND CONNECTOR BETWEEN ECM AND KNOCK SENSOR.
- If OK proceed to step 4.
- If not OK Repair or replace harness or connector.

4. DOES MALFUNCTION DISAPPEAR WHEN A GOOD KNOCK SENSOR IS INSTALLED?
- If YES replace knock sensor.
- If NO check and replace ECM.


INSPECTION USING OSCILLOSCOPE
With the engine racing (4,000 rpm) measure waveform between terminal KNK of ECM and body ground.



The correct waveform appears as shown in the illustration.
Spread the time on the horizontal axis, and confirm that period of the wave is 132 seconds (Normal mode vibration frequency of knock sensor: 7.6 KHz).

NOTE: If normal mode vibration frequency is not 7.6 KHz, the sensor is malfunctioning.