Knock sensor 1 circuit

Flat type knock sensors (non-resonant type) have structures that can detect vibrations over a wide band of frequencies: between approximately 6 khz and 15 khz.

A knock sensor is fitted onto the engine block to detect engine knocking.

The knock sensor contains a piezoelectric element which generates a voltage when it becomes deformed.

The voltage is generated when the engine block vibrates due to knocking. Any occurrence of engine knocking can be suppressed by delaying the ignition timing.

When any of dtcs p0327 and p0328 are set, the ecm enters fail-safe mode. During fail-safe mode, the ignition timing is delayed to its maximum retardation. Fail-safe mode continues until the ignition switch is turned off.

Reference: inspection using an oscilloscope

If the output voltage transmitted by the knock sensor remains low or high for more than 1 second, the ecm interprets this as a malfunction in the sensor circuit, and sets a dtc.

The monitor for dtcs p0327 and p0328 begins to run when 5 seconds have elapsed since the engine was started.

If the malfunction is not repaired successfully, either dtc p0327 or p0328 is set 5 seconds after the engine is next started.

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

1. 1
   Read value using intelligent tester (knock fb val)
2. 2
   Connect the intelligent tester to the dlc3.
3. 3
   Start the engine and turn the tester on.
4. 4
   Warm up the engine.
5. 5
   Select the following menu items: diagnosis / enhanced obd ii / data list / user data / knock fb val.
6. 6
   Read the values displayed on the tester while driving the vehicle.

Hint

The knock feedback value change can be confirmed by running the engine at high load, for example, by activating the air conditioning system and revving up the engine.

1. 1
   Check harness and connector (ecm - knock sensor)
2. 2
   Disconnect the b30 ecm connector.
3. 3
   Measure the resistance between the terminals.

Standard

3. Reconnect the ecm connector.

1. 1
   Inspect ecm (knk1 voltage)
2. 2
   Disconnect the b18 knock sensor connector.
3. 3
   Turn the ignition switch on.
4. 4
   Measure the voltage between the knock sensor terminals.

Standard voltage

4. Reconnect the knock sensor connector.

Fault may be intermittent. Check the wire harness and connectors carefully and retest.

1. 1
   Inspect knock sensor
2. 2
   Remove the knock sensor.
3. 3
   Measure the resistance between the terminals.

Standard resistance

3. Reinstall the knock sensor.