Circuit/System Description

WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.

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 that varies, depending on the vibration levels detected during engine operation. The ECM receives the KS signal through 2 isolated signal circuits for each KS. The ECM adjusts the spark timing based on the amplitude and frequency of each KS signal. The ECM learns a minimum noise level for each sensor at idle speeds, and uses calibrated noise level values for the rest of the RPM range. The ECM should monitor a normal KS signal within the noise channel.