I play through a Telecaster and split into two 2x12 tube amps.

They're stacked like this:

Top - Carvin MTS 3212: treble only

Bottom - Twin Reverb: mids and bass

Now, I've been wanting to put effect pedals that apply to only one amp or the other.

For instance, I've been wanting to use an overdrive on the Twin, but NOT the Carvin. This would keep overdrive the lowend/midrange while keeping the treble end intact (which is exactly what I want).

Another thing I wanted to do was use an EQ pedal that goes to the Carvin amp and boost the really high end frequencies - giving much more of a cutting sound out of that amp.

The only real way to have pedals work for one amp but not another is to put them after the splitter - like this:

EQ --- Treble Amp
/
Guitar --- Splitter
\
Overdrive --- Low/Mid Amp

However -

Whenever a pedal is plugged in after the splitter, NO SOUND seems to come out whatsoever.

I'm not too familiar with electronics, so I don't know exactly why this is the case. I heard something about how a splitter halves the impedance of the signal. I don't know if this is what is causing the problem.

Is there any way to achieve what I'm trying to do?

I just realized my diagram didn't go through -

a correction:

...........................EQ - Treble Amp
......................../
Guitar....Splitter
........................\
...........................Overdrive - Bass/Mid Amp

what splitter pedal are you using? You probably need to buffer your output, but you should get some sound regardless.

I'm using a Morley A/B/Y pedal.

How exactly would I be able to buffer the output?

if both amps are on all the time a simple y-cable is the easiest and cheapest way (see s. albini...).
..............................................effect(s) A----amp A
........................................... /
guitar--effect(s) for A & B--<
............................................\
..............................................effect(s) B-----amp B

NOTHING comes through? Are you sure the pedals are alright? There should be some signal, even if it's weaker...

yeah, something is wrong here. that's exactly how the ABY is meant to be used, or one of the intended ways anyway. and i've never had any problems putting effects after the split.

do you have any true bypass pedals you can use? if you put true bypass pedals after the ABY and still have problems... then I dunno what it could be, honestly. true bypass pedals, if turned off, are basically the same thing as no pedals at all.

do you have a tuner? put it at the front of the signal path, right after the guitar. that should ensure that you don't have any impedance issues. and if it's got two outputs, like the Boss TU2 does, you can try removing the ABY and just using the TU2 to split your signal, and see if that solves your problem.

Did the splitter ever work?
Battery good?
Correct I/O wired?
Somethings wrong.