So we know the wiring is different for the cars and the s5 needs to see voltage at all times.

I have come to the conclusion that you cannot strait wire the s terminal to the b post to *** this problem as others have done.

my question is do you just run the s terminal to the battery and call it a day, or do you have to actually run a wire from the b post as well to the battery

It would seem that the alternator wouldnt read from the b post, but all the wiring conversions show the b post going to the battery, yet most people say they just rewired the s terminal. so which one is it?

 

Covered before, search forums. You need to remove a wire and add another one somewhere else.

 

install it like it was a s4 alt. S to battery + and L to the white wire on the old plug and leave the black alone.

 

You can, but it's not what I'd do. The factory wiring for S5's and FD's powers the S terminal through the EGI fuse as per these schematics.

Alternator schematics: https://www.rx7club.com/attachment.p...hmentid=199213
Alternator pin-outs: https://www.rx7club.com/attachment.p...hmentid=170065

You run a wire from the S terminal to the wire from the EGI fuse. There is no need to run another wire to the B post.