The Knock Sensor (KS) system uses one 3-wire flat response sensor. The sensor uses a piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The amplitude and frequency are dependant upon the level of knock that the KS detects. The KS is connected to the engine control module (ECM) by a signal circuit and a low reference circuit. Both KS circuits are protected from electromagnetic interference by a shielding ground circuit. The shielding ground circuit is grounded through the ECM.
The ECM learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the engine speed range. The control module uses the minimum noise level to calculate a noise channel. A normal KS signal is within the noise channel. As engine speed and load changes, the noise channel upper and lower parameters change to accommodate the normal KS signal, keeping the signal within the channel. In order to determine which cylinders are knocking, the ECM only uses KS signal information when each cylinder is near top dead center (TDC) of the firing stroke. If knock is present, the ECM detects that the signal is outside of the noise channel
Removal & Installation
- Disconnect the negative battery cable.
Remove the intake manifold bracket bolts and bracket.
- Disconnect the Knock Sensor (KS) electrical connector.
- Remove the knock sensor bolt.
- Remove the knock sensor.
- Install the knock sensor and tighten the bolt to 15 ft. lbs. (20 Nm).
- Connect the KS electrical connector.
- Install the intake manifold bracket. Tighten the upper bolts to 18 ft. lbs. (25 Nm). Tighten the lower bolts to 33 ft. lbs. (45 Nm).
- Connect the negative battery cable.