Common Delco SI Series Alternator Wiring Diagram | Smith Sep 22, 2016We are commonly asked how to wire the Delco SI series alternators upon maintenance or upgrading from an older generator. While this series of unit often runs as a self exciting one wire, agricultural applications also used 3 wire connections to the alternator. If you are looking for the no charge indicator light on the Wiring a Delco (GM) Alternator - hartin Wiring an alternator . This diagram shows how to wire a Delco (GM) internally regulated 3-wire alternator. This particular model (10SI, used in the 1970s and early 80s) is the one you'll find on the generation of GM cars most often used in demolition derbies.