Electronic Spark Control (ESC)

Ignition Circuit:

Knock Sensor Circuit:

The Electronic Spark Control (ESC) system is comprised of a knock sensor and the ECM/PCM. The ECM/PCM monitors the ESC signal CKT 496 to determine when engine detonation occurs. When the knock sensor detects detonation, the ECM/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.