Chevy 4.3l Alternator Wiring Question

A 10SI or 12SI (Delco) alternator?

 

Pic? Regulator inside the alternator?

Likely it's a 10SI. This is the common "modern" Delco alternator with an internal regulator.

if you have an indicator light, the wire to it comes from the ignition switch (hot with key on), to the light, and to the exciter terminal on the alternator (one of th two connections on the plug). With no light, you need a resistance wire to the exciter (or a diode - but GM and Jeep never used diodes AFAIK).

 

use the accessory terminal or it will run after you shut the switch off.

 

A light bulb (or a resistance wire) provides enough load between the alternator and ignition to prevent run-on. Jeeps are wired to the ignition side, not the accessory side, and they have a resistance wire. My J20 is wired to an alternator light from the ignition side, and it shuts off fine.

 

If the alternator is the original one that came with the 4.3L engine, it is more than likely a Delco CS130. Google CS130 wiring diagram and you will find multiple examples. The "L" terminal is the one you want for the indicator light. You must have the light or a resistor in the L terminal circuit or you will damage the alternator's internal regulator.

 

Your picture confirms a CS series alternator. You can verify if by looking at a picture of one at Rockauto.

 

It’s not a ground it “grounds” the light until the alternator starts charging then the light goes out. Look here. Catalog Catalog

 

I really could find a wiring diagram for my year of S-10. I ended up buying a factory service manual. This was a big help. It showed every wire, every connecter and where they went to.