Circuit Description

Knock Sensor (KS) is used to detect engine detonation. PCM retards engine spark timing based on KS signal. PCM supplies KS with a 5-volt signal which KS circuitry pulls down to about 1.3 volts when on knock is detected. Knock sensor produces an AC voltage signal that rides on the 1.3 volt DC. Signal amplitude and frequency are dependent on amount of knock being experienced.

PCM determines whether knock is occurring by comparing KS signal level with that of voltage level on noise channel. Noise channel allows PCM to reject a signal that appears to be a false signal, caused by normal engine noises. If PCM determines that an abnormally high noise still detects DTC P0327 will be set.