| 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 under intake manifolds, on inside of cylinder block. Knock sensors generate voltage when engine block vibrates due to knocking. If engine knocks, ECM will retard ignition timing. If DTC is set, ECM will operate in fail-safe mode (maximum timing retardation). DTC is set when there is no knock sensor signal to ECM with engine speed of 1700-5400 RPM. DTC P0325 is for knock sensor No. 1 on left side of cylinder block. DTC P0330 is for knock sensor No. 2 on right side of cylinder block. 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 7.7 kHz. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.