Sorry if this has been posted before, I rarely find forum search functions to operate properly.

I have a customer with a 99 Voyager, 3.3. Bare bones van, no power  anything. She came to me saying that she got in the van, started it,  then it died in a couple seconds. Vehicle will no longer crank at all.
Ignition switch is working properly, all fuses are good. Starter fuse  receives power when key is switched to the Start position, but no crank.  All sensors are receiving their 5v input, but the coil pack has no  incoming power, so even if I turn the key on, and open up the starter  relay and manually switch it, the motor cranks but will not start. Fuel  pump is priming and pressure is on par. ASD relay switches when the  starter relay is closed manually.

CCD Bus + and - are both perfect, communication between modules seems to be working as intended.

I did a bit of reading about the solder crack on the back of the  cluster, which I found to be true in this vehicle. Fixed that to no  avail. I'm working from home on this one, so my diagnostic capabilities  are a bit low, but I'm running out of options short of telling her it  needs a computer, which I know it doesn't. I used to manage a small  service station a few years ago, and ran into this exact same problem on  the exact same year van. I called 3 of my master tech friends, and we  couldn't find anything wrong with it. New computer didn't fix that van,  either.

I removed the battery and engine compartment fuse box, removed all the  wiring sheaths under it and found no flaws/corrosion/splits, anything of  that nature.

As of this point I'm at a loss of what to try next. I have a lingering  suspicion that the Trans Range Sensor is the problem, but my local Dodge  dealer tells me, that particular sensor will not kill a running motor  if it should happen to die while the engine is operating, which leads me  back to square one. The dealer also tells me that this model year  doesn't have a range sensor, and they can't order me one without taking  mine out, because they don't list it. Have I stumbled upon the unicorn?

The dealer is incorrect.  There is a TRS on a 1999 minivan with a 3.3, that started in 1996.
The computer won't keep the engine from cranking, unless something fails  in the park/neutral sense or the logic to prevent cranking while the  engine is running fails.  
You need the wiring diagram from the factory manual, but the ground goes  from the transmission through the computer to the starter relay, pin  85.
The switch feeds pin 86 of the relay, pin 30 is battery feed and pin 87 is relay output to the starter.

When I had a no crank problem on my 96 mini which is a conventional 3  speed, it ended up that the computer was the problem.  Some may remember  when I bought this from poster "lugnut".  The problem was very  intermittent and only showed up occasionally so it took me forever  (several months) to finally condemn the computer.  His mechanics never  could figure it out and that is why he sold it.  What I ultimately found  out is that computer imposes a ground on the coil side of the starter  relay to pull the relay down.  The reason the computer does this is that  there is a logic circuit in the computer that will not allow the  starter relay to close if the engine is running.  Remember on the old  cars, if you accidently turned the ignition switch to start with the  engine running, you would get that horrible grinding noise?  Well that  won't happen anymore because the computer will not let the starter relay  pull down.  Through my testing, I eventually figured out that the  computer would not impose a ground to the relay and that made the  vehicle totally non-responsive... as if you had a bad ignition switch.

The fact that your ASD and fuel pump relays are pulling down but you  have no power to the coil packs, makes me suspicious that there is just a  bad connection somewhere.  However, you can never completely rule out  the computer.  You might unbolt the PDC and clean the contacts of every  plug on the bottom with contact cleaner and do the same with the  computer connector.

OK so a little testing this morning. Pin 85 has a full time ground, no  matter the position of the key. I was under the assumption that this was  a switched ground, but maybe I'm wrong.
86 receives power with Key-Start
30 has full time power
and 87 works, because I can force the starter to spin by closing the relay.

Now, with everything here seemingly working as intended, why won't the  starter engage? In a no-crank scenario, this relay is working fine.