This is a compilation of knowledge gained in the troubleshooting of the wiring of an s6 alternator into a s4 electrical system with the original thread at: http://www.teamfc3s.org/forum/showth...0&pagenumber=1
Through the contributions of many people (KYPREO, Icemark, silverrotor, HiminiRacing, Fedds, fc3s7, RXtasy and myself) we finally resolved the proper way to wire the s6 alternator without causing a drain on the system through improper wiring.
The switch from the FC alternator to the FD alternator has caused many a dead batteries and headaches for the people who have made the switch. I wiring seems simple but a small oversight is easily made which results in a small drain on the battery while the car is off.
Wiring an s5 or s6 alternator up in the s4 fashion (simply trim the old connector off and adapt it) will create an electrical draw. The problem with the way the alternator was wired stock is that the FD alternator expects to see 12V+ with the ignition off, but it actually sees 0V (ign.switched +12v on a s4), Because the output terminal (B) is connected, but the regulator sensed 0V, it will actually try and charge with the battery off, causing a current drain, and potentially fry the regulator. The diagram shows how to wire correctly.
If your regulator is fried (can be checked by most local auto parts stores) they are fairly cheap to replace ($15-20), and a note, there are 4 in the FD alternator.

Why would you want to switch to switch to a FD alternator? The stock FC alternators make just enough power to suffice for the stock electrical system. With many RX-7 owners installing aftermarket stereo systems, security systems and other electrical accessories the alternators soon max out, resulting in dimmed headlights, warmer A/C and all sorts of annoyances. Here are some specs on the output of the different series alternators:
~s4 (86-88) 60amps
~s5 (89-91) 80amps
~s6 (93-99) 100 amps

If you no longer have the stock air pump it is recommended to get a dual belt pulley for the alternator as it may slip at higher rpms with only one belt. Also you will need a different bolt-washer-nut combo to put through the tension bracket and ear of the FD alternator as the FC ear is threaded and the FD is not.

If you are interested in an FD alternator Silverrotor offers everything needed to switch.
https://www.rx7club.com/showthread.p...0&page=1&pp=15

 

except the stock output of a S4 alt is 70 amps not 60

 

I thought 70 amps (S4) was overrated...that's what i read somewhere anywayz.

 

I just did that mod after fooling with a dead battery in my S4 vert with an S5 alt.
I bet that cures it, but it'll sit a few days more to be sure.

 

I bought my Alt upgrade last year from sliver rotor and hooked it up just like he said. I have never came out to a dead battery. How long would it have taken to drain it...?

 

I noticed mine would crank rather slow (new battery) after a couple of days. Battery completely dead after 2 weeks sitting. You probably won't notice it if you drive everyday.

 

There will only be a problem if the car is a s4 mind you. But there have been a handfull of people that havn't had a problem with the stock wiring on their cars, I think it has a great deal to do with the battery type, driving habits and what all is done to the electrical system. You may not ever see a problem with your car wired that way, but this IS the correct way to wire it on a s4.

 

ok, this is a quote from a post I made on teamfc3s a while back. Don't worry, this will confirm what psyclo is saying:

I have an S4 with S5 alt (same idea for S6 alt on S4), and it's pretty clear the battery will drain if you don't wire things correctly. Also, the regulator could get damaged.
I had talked about this way back then saying there was a problem but nobody cared at that time.
As previous poster said, if you drive your car regularly, you probably won't notice a thing.

iougs-

 

ok, this is a quote from a post I made on teamfc3s a while back. Don't worry, this will confirm what psyclo is saying:

I have an S4 with S5 alt (same idea for S6 alt on S4), and it's pretty clear the battery will drain if you don't wire things correctly. Also, the regulator could get damaged.
I had talked about this way back when saying there was a problem but nobody cared at that time.
As previous poster said, if you drive your car regularly, you probably won't notice a thing.

iougs-

 

Icemark, I guess I couldn't convince you? I was right about the LR and LS type differences.

Here is another reference.




http://www.rx7.org/public/altxref.html





I'm glad the misinformation has been disposed of (albeit when I was "wrong" and you so humbly "corrected" me it was available for anyone and everyone to see).

 

That was the thread I created to say that something was fishy, and then I saw the teamfc3s thread which was talking about the same thing, and then KYPREO gave his valuable input, and the problem was solved.

https://www.rx7club.com/forum/showthread.php?t=320618

Then rx7.org changed the instructions on their page after that, I don't know if mikeL changed his though

So at the end, it's all good.

hugues-

 

No need for pointing fingers and such garbage. Problem solved, use it as a refrence not points scoring.

 

How much different is it to wire the s6 alt into a ser3 gslse?

 

No I disagree with the solution, as Mazda changed it on later models (fixing the extra draw problem no doubt).

 

UPDATE

My battery would be dead after 2 weeks sitting. Did this mod, waited THREE weeks, car fired right up. Looks like this was indeed the solution to the s5 alt in the s4 problem!

 

since the S terminal and the B terminal go to the same place. Could you just wire the S terminal wire to the B post? I just installed my alt. this way and dont want to turn it on until I get a responce. THANKS

 

Well I could wait. So I turned it on and it seemed to do fine. But Im still not going to drive it until I get an oppenion from one of you.

 

this thread is fairly old. you might have better luck checking out the sticky from silverrotors threads