Electronic Spark Control Module: Description and Operation

Ignition System:

PURPOSE
The Electronic Spark Control (ESC) system is designed to retard the spark timing up to 20° to reduce spark knock (detonation) in the engine. This allows the engine to use maximum spark advance to improve driveability and fuel economy.

LOCATION
ESC module - L.R. corner of engine compartment.
Knock sensor - Outboard side of R.H. cylinder bank, in the rear.
ECM - In the L.H. kick panel.

OPERATION
Varying octane levels in today's gasoline can cause detonation in an engine. Detonation is called spark knock.

A knock sensor is mounted on the engine block. It is connected to the ESC module. The knock sensor, in response to engine knock (detonation), sends a signal to this module. The module decodes these signals, and if they indicate spark knock type noise, a retard signal is sent to the ECM which in turn retards the spark advance.

The ESC module sends a voltage signal (8 to 10 volts) to the ECM when no spark knocking is detected by the ESC knock sensor, and the ECM provides normal spark advance.

When the knock sensor detects spark knock, the module turns OFF the circuit to the ECM. The ECM then retards EST to reduce spark knock.