Circuit Description

The knock sensor (KS) system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The ECM monitors 2 separate KS, one on each side of the engine block. Each KS produces an AC voltage signal that varies with different engine speeds and loads. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM receives the KS signal through a signal circuit. The KS ground is supplied by the ECM through a low reference circuit. The ECM uses the KS signal to calculate the average voltage, then assign a voltage range value. The ECM will then monitor for a normal KS signal within the assigned voltage range. If the ECM malfunctions in a condition that will not allow proper diagnosis of the KS system, DTC P0325 will set.