GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Ignition System


Most of the S/T trucks utilize an HEI distributor ignition system. On earlier models, this distributor is equipped with mechanical and vacuum timing advance devices to adjust the ignition spark advance curve. Most later model distributors are equipped with Electronic Spark Timing (EST) and ignition spark advance is electronically controlled through a computer module.

For more information on these ignition systems, please refer toChapter 2of this manual.