Circuit Description

The knock sensor (KS) produces an AC voltage at all engine speeds and loads. The powertrain control module (PCM) then adjusts the spark timing based on the amplitude and frequency of the KS signal. The PCM uses the KS signal to calculate the average voltage. Then the PCM assigns a voltage value. The PCM verifies the KS and related wiring by comparing the actual knock signal to the assigned voltage range. A normal KS signal should stay within the assigned voltage range. This DTC will set if the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system.