Circuit Description

VCM utilizes knock sensors to detect engine detonation, allowing VCM to retard Ignition Control (IC) spark timing based on knock sensor signal received. Knock Sensor (KS) circuitry within sensor pulls down VCM-supplied 5-volt DC signal, so that under a no-knock condition signal on KS, circuit measures about 1.3 volts. Sensor produces an AC signal that rides on DC signal. Signal amplitude and frequency are dependent upon amount of knock experienced.

VCM contains a replaceable KS module. KS module contains circuitry that allows VCM to utilize KS signal and diagnose knock sensors and circuitry. VCM will set DTC if KS module is missing or faulty causing a continuous knock condition. Conditions for setting DTC:

• DTC P0327 is not active.
• Engine run time at least 120 seconds.
• System voltage is 10-17.1 volts.
• VCM detects a problem with KS module circuitry that causes a continuous knock condition.
• Conditions present for up to 0.5 second.