DeVille DHS V8-4.6L VIN Y (2000)
Knock Sensor: Description and Operation
Knock Sensor (KS)
The PCM uses a Knock Sensor (KS) to detect abnormal vibration in the engine (detonation/spark knocking). Mounted in the engine block, under the
intake manifold, the knock sensor produces an AC signal at all engine speeds and loads. The PCM then adjusts the spark timing based on the amplitude
and frequency of the KS signal.
A knock sensor module is no longer used to diagnose the knock sensor system. The circuitry is integrated into the PCM. The PCM uses the knock sensor
signal to calculate an average voltage. Then, the PCM assigns a voltage range above and below the average voltage value. The PCM checks the knock
sensor and related wiring by comparing the actual knock signal to the assigned voltage range. A normal knock sensor signal should vary outside the
assigned voltage range.
If the PCM malfunctions in a manner that will not allow proper diagnosis of the knock sensor and related wiring, DTC P0325 will set. If the PCM detects
a knock signal input within the assigned voltage range, DTC P0327 will set. Refer to Knock Sensor (KS) System for a complete description of the knock
sensor system.
