| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. |
Circuit Description
Knock sensors are located on either side of cylinder block underneath lower intake manifold assembly. Sensor generates voltage when engine block vibrates due to knocking. ECM retards timing based on this voltage signal. DTC P0325 and P0330 are set when there is no knock sensor signal to ECM with engine speed of 2000-5600 RPM. DTC P0325 is for knock sensor No. 1 on right bank. DTC P0330 is for knock sensor No. 2 on left bank. Possible causes are
- Open or short in knock sensor circuit.
- Knock sensor (loose).
- Faulty ECM.
Diagnostic Aids
Normal mode vibration frequency of knock sensor is 7.1 kHz. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.