Circuit/System Description
WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
For an overview of the component/system, refer to Electronic Ignition System Description
| Circuit | Description |
|---|---|
| Signal - Terminal 1/A | The control module input circuit has an internal resistance connected to 5 V. |
| Signal - Terminal 2/B | The control module input circuit has an internal resistance connected to 1.33 V. |
| Component | Description |
|---|---|
| B68 Knock Sensor | The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The amplitude and frequency depend upon the level of knock that the knock sensor detects. |
| K20 Engine Control Module | The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly. |
The knock sensor measures vibrations of the engine block. To some extent it is comparable to a microphone. The sensor produces an AC voltage that is proportional in frequency and amplitude to the vibrations. The ECM can deduce from the signal if and which cylinder is knocking. This enables the ECM to adjust the spark timing so that the best fuel efficiency is gained. The ECM learns a minimum knock sensor noise level at idle and uses calibrated values for the rest of the engine speed range.