Ignition Timing: ESC

On vehicles with the 4.3L V6, additional spark timing control is provided by the Electronic Spark Control (ESC) system. This system consists of two main components: the ESC module and the ESC knock sensor. See Data Sensors.

Under normal conditions (no spark knock), the ESC module sends a voltage signal of 8-10 volts to the ECM, and the ECM provides normal spark advance. If the knock sensor detects spark knock, it signals the ESC module which then turns off the voltage signal to the ECM. The ECM retards ignition timing as needed to reduce knock. A fault in the ESC system should set Code 43.