GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Description & Operation


The ESC system has three components:

  1. ESC Module
  3. ESC Knock Sensor
  5. ECM (some later models may use a PCM, VCM or VCM-A depending upon application)

The knock sensor detects abnormal vibration in the engine. The sensor is mounted in the engine block near the cylinders. If equipped, the ESC module receives the knock sensor information and sends a signal to the ECM. The computer control module then adjusts the ignition timing to reduce spark knocking.

The ESC module sends a voltage signal 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.