Electronic Spark Control Module: Description and Operation

Electronic Spark Control (ESC) Diagram:

NOTE: Because different models and engine applications vary in wire colors, circuit numbers, and pin numbers, the above image is a typical example. Refer to COMPUTERS AND CONTROL SYSTEMS/SCHEMATIC AND ROUTING DIAGRAMS for specific schematic applications.

PURPOSE
The Knock Sensor (KS) retards spark timing up to 15° to reduce spark knock.

OPERATION
The KS has two major components:
- KS module (part of MEM-CAL)
- Knock Sensor
The knock sensor (KS) detects abnormal vibration (spark knocking) in the engine and produces an A/C output voltage which increases with the severity of the knock. The A/C signal generated by the knock sensor inputs to the KS portion of the MEM-CAL which signals the PCM to adjust timing. Resistance within the knock sensor circuit reduces the PCM 5 volts down to 2.5 volts.

LOCATION
MEM-CAL in Electronic Control Module.