Circuit Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The system uses two KS located under the intake manifold. KS 1 is located at the front of the engine. KS 2 is located at the back of the engine. Each KS produces an AC voltage that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and frequency of the KS signal. The PCM receives a signal from each KS through a signal circuit. The KS ground is supplied by the engine block through the sensor housing. The PCM uses each KS signal to calculate an average voltage range value. If the KS system is operating normally, the PCM should monitor the KS voltage varying above and below the voltage range. If the PCM detects the KS signal voltage within the voltage range, or the KS signal is not present, a DTC will set. DTC P0327 refers to the front KS. DTC P0332 refers to the rear KS.