LX470 — NEW FEATURES 29 c. Operation The knocking vibration is transmitted to the steel weight and its inertia applies pressure to the piezoelectric element. The action generates electromotive force. Steel Weight Piezoelectric Element Inertia 214CE08 d. Open/Short Circuit Detection Resistor During the ignition is ON, the open/short circuit detection resistor in the knock sensor and the resistor in the ECM keep the voltage at the terminal KNK1 of engine constant. An IC (Integrated Circuit) in the ECM is always monitoring the voltage of the terminal KNK1.
If the open/short circuit occurs between the knock sensor and the ECM, the voltage of the terminal KNK1 will change and the ECM detects the open/short circuit and stores DTC (Diagnostic Trouble Code). ECM Piezoelectric Element 5 V Flat Type Knock Sensor KNK1 200 k Ω EKNK 200 k Ω IC Open/Short Circuit Detection Resistor 214CE06 Service Tip In accordance with the adoption of an open/short circuit detection resistor, the inspection method for the sensor has been changed. For details, see the 2006 LEXUS LX470 Repair Manual (Pub. No. RM0030U).