I need to know which wire, from the ignition switch to the alternator, should be used to kill power to the alternator. I'm definitely not an expert when it comes to anything electrical, but looking at the helms manual, it appears that the wire I need to use is the black/yellow coming out of the ignition switch.

 

On a single pole switch you need to connect the battery + and the alternator charge wire (thick black wire that runs behind the engine to the main under hood fuse box) to one side of the switch and both under hood fuse boxes to the other side. The charge wire needs to remain connected to the battery to drain any charge from the alternator even when the switch is off.

The charge wire connects to the main under hood fuse panel on a 100A fuse. You need to remove it from there and connect it directly to the battery + terminal (use an inline fuse if you must).

Your switch will cut power between the battery + terminal and the two under hood fuse boxes. If you don't move the charge wire to the battery directly then the alternator will continue to power the fuse boxes when the switch is off.

 

I'm using a 4 terminal switch. My cagebuilder is installing this for me, but his experience is with miatas. Evidently they only have 1 wire coming from the ignition switch and this is how he cuts power to the field wire. Hence the problem, we have 4 wires coming out of the ignition.

 

Yeah, I have a 2 pole switch as well but I use it as a 1 pole. Getting access to the field wire was way to big a problem so I took an alternate route. I think the Yellow/Black is the one you want but I never got far enough to test that theory.

 

if you cut the battery pos and alt wire it will kill it.
no need to bypass ignition stuff it will not work.

I have 4 girth wires going to my cutoff.
from batt pos and alt
to batt pos in underhood box and where ever the alt cable went.

 

I need more help guys! I'm completely over my head with this one and trying to learn as I go. I forwarded your answers to my guy and they were no help to him either. If anybody has another suggestion or any other helpful advice, please pass it on to me.

 

I don't understand that. Cthree's post seems very clear. Is there a reason you can't do it the way he describes?

 

I can't go out to the garage and look at it, so no it doesn't make sense to me. In the defense of my cagebuilder, cages are really all he does. He's done switches and things on miatas before but never an S2000. He just wants to make sure he does it right and he's not familiar with the wiring on our cars.

 

It seems to me that cthree had a similar problem since he thinks the yellow/black is what we need to use. He just found an alternate way to do it.

 

OK, I'm looking at page 4-21 of the Helm manual. It shows a black wire connecting from the alternator to the fuse box. Eric said to disconnect it from the fuse box and connect it to one pole of the switch. You should also disconnect the battery + cable from the fuse box and connect it to that same pole of the switch.

Then you connect the fuse box to the other pole of the switch. Seems pretty straightforward. I just went and looked at my car and I thought I could spot everything pretty easily.

But I guess you could try the black/yellow instead. That does seem to be the one going through the ignition switch. But in that case, what't the problem? Can't you find the black/yellow?