How to Wire an AC Delco 3 Wire Alternator | It Still Runs The AC Delco 3 wire alternator was used in most General Motors products, and many types of heavy equipment, for a long time, which makes it readily available. This alternator has the advantages of high output, compact design and ease of use. With the proper Bosch Alternator Wiring. Torana. Please help Bosch Alternator Wiring. Torana. Please help I recommend it also if running a painless harness as they can have some voltage drop issues . The diagram is of a later model Bosch alternator (vn onwards) . 01-11-2012, 09:13 AM #10. toranahoon. Newbie the S wire is a remote Voltage sensing wire, 3-Wire Alternator Wiring Instructions | It Still Runs Alternator wiring is easier than in the past due to the use of plugs and sockets which are usually different sizes ensuring you wire your alternator correctly. Additionally, most alternators have internal voltage regulators resulting in the need to only wire three connections instead of four.