Electronic Spark Control System (ESC)

The 4 basic components of the Electronic Spark Control (ESC) system are the detonation sensor, HEI (EST) distributor, controller and the ECM. When detonation (engine knock) occurs, the detonation sensor sends an electrical signal to the ESC. The controller amplifies this signal and transmits it to the ECM. The ECM will retard spark timing until signals from the detonation sensor cease.

Fig 1: HEI (EST) Distributor with Integrally Mounted Coil

Courtesy of GENERAL MOTORS CORP.

Fig 2: Schematic of Electronic Spark Control System

Courtesy of GENERAL MOTORS CORP.