Skervey Reader
7/24/15 7:52 a.m.

Hey guys as the title implies I am wiring up a 2G alternator for my rx7 302 swap. I have been around on the mustang sights and everyone talks about the 3G upgrade and they don't have much to say about the 2G. Here is a diagram I found that seems to explain it all but I have a quick question.

Looks simple all the wires run to a fuse then to the battery/car except for the green wire. I have that done but I want to know and understand the use of the green wire before I wire it up. I am thinking that the green wire is a cut on switch that turns the alternator on so it know to make power. Am I thinking about that right? If so it should not need a large gauge wire running to it and should just need a simple 12v source ignition found somewhere under the hood.

Thanks for the help guys! Slowly going to be a wiring guru thanks to yalls help!

DaveEstey PowerDork
7/24/15 8:03 a.m.

Eh not really. When the alternator isn't turning the green wire is grounded, which means the dash light illuminates. Once the alternator is generating power it's no longer grounded, so the dash light goes off. Simple.

Skervey Reader
7/24/15 8:45 a.m.

Ok so maybe I can leave this alone for a little bit and run the car without the wire hooked up. On grannys site they don't talk much about the alternator install. I don't see any wire that says its for the dash light but I plan on running a voltage meter in the car so I always know without a question if its good or not.

Thanks for the fast response!

edizzle89 HalfDork
7/24/15 8:49 a.m.
DaveEstey wrote: Eh not really. When the alternator isn't turning the green wire is grounded, which means the dash light illuminates. Once the alternator is generating power it's no longer grounded, so the dash light goes off. Simple.

and if you dont run it to a dash light it still needs some kind of equal resistance on that wire similar to the dash light.

Skervey Reader
7/24/15 9:01 a.m.

So maybe just wire up a little light under the dash so it has the correct resistance?

DaveEstey PowerDork
7/24/15 9:06 a.m.

I just used a dash light from radio shack in my system.

ross2004 Reader
7/24/15 9:11 a.m.

Any reason for not running a 3G? If anything it looks much better than the 2G.

Dusterbd13 UltraDork
7/24/15 9:38 a.m.

Yup. Just a simple light inline. It's the signal wire to tell it to charge. No light means you'll burn the alternator up.

Skervey Reader
7/24/15 10:26 a.m.

Grate I have a light from the security system i can use. And as far as running the 2g it's because I have it. If this ones burns up I will upgrade but I don't have a huge need for power. Tiny radio, hand crank windows sunroof is broken and lights. The 2g should be more then enough.

pjbgravely Reader
7/25/15 9:11 a.m.

I believe I hook one of those alternators up to a small tractor. I increased the resistance to change the max charging rate to keep it from stalling out the engine. I remember having to keep the switch off to be able to start the engine. I also remember it not charging at all without the green wire hooked up.

iceracer PowerDork
7/25/15 9:36 a.m.

You need current through the green wire to excite the alternator.

novaderrik UltimaDork
7/25/15 12:31 p.m.

looks like wiring up a Delco CS series alternator, but in typical Ford fashion they made it a little more complicated for no good reason.. just put a small light bulb inline on that green wire and it should work.

Skervey Reader
7/27/15 8:51 a.m.

Thanks for the help guys I go have a very small bulb between the green wire and grounded it to the body. I will have to see if the bulb still works it might be burned out I just grabbed it from the alarm system.

Dusterbd13 UltraDork
7/27/15 9:05 a.m.

you don't want to ground the bulb. that will just create a short. take one wire from bulb, hook to green wire on alternator. take other wire from bulb, connect to switched hot source. make sure body of socket doesn't ground out.

the alternator, when not charging, creates a ground to light the bulb. when it is charging, light goes out.

JohnJackson New Reader
6/14/19 2:07 a.m.

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jfryjfry Dork
6/14/19 3:01 a.m.

But do you have anything that can meet the taxing demands of my canoe’s electrical system?  

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