P0325
DTC PO325KNOCK SENSOR CIRCUIT MALFUNCTION (KNOCK)
Description
- The knock sensor senses engine knocks and sends a voltage signal to the Engine Control Module (ECM) depending on the degree of the knock.
- This signal information is used for spark timing learning control to provide optimal spark timing.
- The knock sensor is bolted to the cylinder block at #4 piston. It senses knocks which can occur in any cylinder. Its components are a weight which moves up and down when it senses vibrations a piezo element which produces a voltage and a resistor which senses a broken circuit (all these are molded into a single unit). When the sensor senses engine knocks, knocking vibration is conveyed to the weight. The up or down movement of the weight is applied to the piezo element as a pressure difference. The Knock Sensor will then produce a voltage signal in relation to the degree of the knock.
DTC Detecting Condition
Immediately at fault recognition
Trouble Symptom
- Poor driving performance.
- Knocking occurs.
1. Check harness.
a. Turn ignition switch to "OFF".
b. Disconnect connector from ECM.
c. Measure resistance between ECM harness connector and body.
[CHECK]: Connector & terminal:
(B84) No. 30 - Body/700 K-Ohms or more.
[YES]: Go to step 2.
[NO]: Go to next [CHECK].
[CHECK]: Connector & terminal:
(B84) No. 30 - Body/40O K-Ohms or less.
[YES]: Go to step 3.
[NO]: Go to step 4.
2. Check Knock Sensor.
a. Disconnect connector from knock sensor.
b. Measure voltage between knock sensor connector and body.
[CHECK]: Connector & terminal:
(E14) No. 1 - Body/700 K-Ohms or more.
[NO]: Check and repair the following items.
- Open circuit of the harness between knock sensor connector and ECM connector
- Poor contact of the knock sensor connector
- Poor contact of coupling connector (B21).
[YES]: Go to next [CHECK].
[CHECK]: Check for secure tightening of the knock sensor installation bolts.
[NO]: Tighten knock sensor installation bolts securely.
[YES]: Replace knock sensor.
3. Check knock sensor.
a. Disconnect connector from knock sensor.
b. Measure resistance of harness between knock sensor connector and body.
[CHECK]: Connector & terminal:
(E14) No. 1 - Body/400 K-Ohms or less.
[YES]: Replace knock sensor.
[NO]: Repair short circuit of harness between knock sensor connector and ECM connector.
NOTE: The harness between both connectors is shielded. Repair short circuit of harness together with shield.
4. Check input signal for ECM.
a. Connect connectors to ECM and knock sensor.
b. Turn ignition switch to "ON".
c. Measure voltage between ECM and body.
[CHECK]: Connector & terminal:
(B84) No. 30 - Body/2 Volts, or more.
[NO]: Repair poor contact in ECM connector.
[YES]: Even if Malfunction Indicator Lamp (MIL) lights up, the circuit has returned to a normal condition at this time. (However, the possibility of poor contact still remains.) Check and repair the following connectors.
- Knock sensor connector.
- ECM connector.
- Coupling connector (B21).