Knock Sensor #2 Circuit

WHEN MONITORED
With the ignition ON and the engine running.

SET CONDITION
The knock sensor signal circuit voltage (cavity 10) falls below a minimum value at idle or deceleration. The minimum value is from a look up table internal to the PCM and is based on engine rpm.

OR

The fault also sets if the sensor output is above 5.0 volts.

THEORY OF OPERATION
The knock sensor, mounted on the cylinder block below the intake manifold, is comprised of thin piezo-electric ceramic discs bonded to a metal diaphragm.

When engine knock occurs, the diaphragm vibrates along with the piezo-electric discs, producing an electrical signal.
The signal is used by the PCM (cavity 42), to adjust ignition timing to eliminate the knock condition.

PROBABLE CAUSES
- Sensor signal circuit open
- Sensor internally open
- Sensor ground circuit shorted to ground
- PCM Failure