Electronic Spark Control Module: Description and Operation

Knock Sensor Module Location - U Body:

Wiring Diagram For Chart C-5 - Electronic Spark Control (ESC) System Check:

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) system retards spark timing up to 8° to reduce spark knock. This allows the engine to use maximum spark advance to improve driveability and fuel economy.

OPERATION
The KS has two major components:
- KS module
- Knock Sensor
The knock sensor (KS) detects abnormal vibration (spark knocking) in the engine and produces a voltage that is received by the KS module. As long as the KS module sees no voltage from the knock sensor (knock not present), it sends a signal voltage (8 to 10 volts) to the ECM and the ECM provides normal spark advance.
When the module detects voltage from the knock sensor (knock present), it turns "OFF" the signal to the ECM and the voltage at terminal B7 goes to 0 volt. The ECM then retards IC timing to reduce spark knock.

LOCATION
Attached to ECM mounting bracket.