This may depend on knowing what type of "noiseless single" you have in the neck. There are humbuckers that fit in a single coil space, there are "over and under" HBs that have an upper, string-sensing coil and a lower coil just to buck hum, and there are various other noiseless types like Lace Sensors, which are an entirely different thing.
If it's one of the HB types, it can be run in series with the bridge pup, no problem. If it's like a Lace Sensor, running it in series with a regular pickup may (I emphasize "may") be a problem.
So let us know exactly what you have. How may wires come out of it, and what type/colors are each?
I have a simple SPDT switch. (It has 3 lugs)
Is it a two-position switch (on-on) or three position?
Is there a way to wire a configuration where I can switch from the 2 pickups in series, back to just the neck noiseless alone?
Is this all you want, or is there another pickup switch involved, to chose N/N+B/B, perhaps? I haven't worked out if series can be done with a SPDT switch or not, but I'm doubtful that it can be done without another pole, if there is more switching than this involved.
If you just want the N always on, in series with the bridge or by itself (and no provision for bridge alone), you might get that done with just a SP switch. Again, I haven't tried to work it out pending more info here.
Anyway, sorry for all the questions, but we can zero in on a diagram for you with some additional specifics.
Now, before you start firing up the soldering iron, let's let someone vet this first. I'm learning this stuff myself, and I am wrong distressingly often!
But I think this will do the trick . . . I hope!
BTW, the wire colors are arbitrary on my part. The green and red may not be the ones wired together on your HB, and I show the SC ground wire as black, while you indicate it's a bare wire.
If your HB is already wired together (2 of the 4 wires join), just leave it and use the other 2 wires for the connections.
We also don't know the correct phasing between the 2 pickups, but that can be worked out as well, either through testing, or by switching the appropriate wires if the coils are out of phase once you get it wired up.
Technically speaking, your solution will work...... but......
What if the switch fails?
A better way would be to simply let the two pups run in series at all times, and short the single-coil when necessary. (That would be a simple SPST configuration.) Regardless of how the switch might fail in this circuit, (single-coil pup is shorted, or it's not), there will be output of some kind, and thus the show goes on.
On another note, some players might warn about popping sounds when interrupting the ground lead of a pup. I don't think so, mainly because the volume pot is always in the circuit, and presents a significant load that should absorb any transients of that nature. Now if there were no pot, just straight pup-to-amp, then I'd be a bit more concerned.
Now consider that the system will no be "noiseless" when the SC is switched in. No combination of 3 coils can be hunbucking except by accident. Of course, if it's being combined with other coils via the 5 way...
Thx a lot for all the ideas and info on here. You guys are very kind to take the time to help out a stranger.
Your idea sounds great, but I am an electronics idiot, so I wonder if I may make a further nuisance of myself and ask if you might be able to post a diagram or instrctions on how to wire up the config. you suggested?