Electronic Spark Control Module: Description and Operation

PURPOSE
To reduce spark knock (detonation) by retarding timing advance.

OPERATION
The Electronic Spark Control (ESC) system is comprised of a knock sensor and the PCM. The PCM monitors the ESC signal CKT 496 to determine when engine detonation occurs. When the knock sensor detects detonation, the PCM retards timing in small increments of 2° (up to 10°) to reduce detonation. This allows the engine to use maximum spark advance to improve driveability and fuel economy. Retarded timing can also be a result of excessive valve lifter, pushrod or other mechanical engine or transmission noise.