Inspection of Knock Sensor

Fig. 27 Testing knock control sys. with substitute knock sensor:

1. Check the retard function.
2. If the ignition timing does not retard, go to next step.
3. Disconnect the knock sensor connector.
4. Connect a good knock sensor to the vehicle and ground the sensor Fig. 27.
5. Tap the sensor and make sure the ignition timing retards.
6. If the retard operates, replace the knock sensor.