What were the two wires that got ripped out? Did they go towards the tailshaft housing?

P1815 for MM is the switches inside the shifter itself, very common failure item but won't cause transmission limp mode, it's usually an intermittent failure that throws the code meaning the MM will still work but will intermittently stop working.

P0463 is the fuel level sensor failing, common, won't cause any issues except for the gas gauge reading wrong fuel level.

Getting the transmission to shift finally after it's been run a lot and is hot but not while cold is typically a fluid level issue but might also be a pump failure on the transmission, however you aren't throwing the code for the turbine input revolution which would USUALLY be associated with a pump failure.

All these codes can be also caused by an electrical malfunction.

P1754 - input clutch solenoid FUNCTION, can be caused by low ATF pressure.
P1757 - front brake solenoid not functioning, the TCM monitors the amperage and didn't see a change when it was actuated.
P1759 - front brake solenoid FUNCTION, can be caused by low ATF pressure.
P1764 - direct clutch solenoid FUNCTION, can be caused by low ATF pressure.
P1769 - high/low reverse clutch solenoid FUNCTION, can be caused by low ATF pressure

Here's what I think might be the issue, either your front brake solenoid (or wiring) is the issue, if that brake band doesn't engage it's not going to leave 1st gear. This can cause a cascade of codes however you're throwing a LOT of codes that CAN be caused by low fluid pressure, just to verify you are checking the tranny fluid level with the engine running yes? And wiping down the dipstick multiple (even a dozen if needed) times until you finally get a clear reading. Earlier when you added 8 qt on a drain/fill is a huge red flag that something is wrong.

HOWEVER HOWEVER, you say you can mash the accelerator and the engine doesn't rev? Does it do this in park/neutral as well? All those tranny codes can also be because the expected target gear ratio to accelerator pedal position is wrong. I didn't think that engine revolution was controlled at all by the TCM except when in limp mode but if you can't rev while in park/neutral this could all be an APP switch issue.

At this point I think you need to go to Nissan/Infiniti for a diagnostic rather than pouring time and money into the DIY garage, the Consult-II/III dealership tool has a full suite of diagnostic steps to read data from every solenoid as well as every other sensor on the tranmission.

Or buy an entire replacement tranny WITH TORQUE CONVERTER and do a tranny swap, with all those "can also be caused by low pressure" codes there is a decent chance your converter failed, you had black fluid so there's definitely some worn components inside the clutch packs/brake sleeves, you might want to cut your losses on this transmission and just source a used replacement.

 

Thanks again. The accelerator pedal issue just started the the last time I put the VB back in. It doesn't rev at all, P, R, D, never. I couldn't imagine how the VB or TCM would affect this .

I'm going you put the VB assembly back in one more time today. I soldered the wires back into the connector, it looks pretty good now.

 

If it shows the correct gear on the dash when you're in P, N, R, D then it sounds like your accelerator pedal switch died for some reason. When it rains it pours I suppose, you can bench test it with a 3x AAA battery holder to supply roughly 5vdc to each side of the pedal switch while you use a digital meter to measure the voltage swing. Correct voltage parameters are in the FSM section EC - Engine Controls, just look up the DTC code for the APP, can't remember what page it's on.

I would scan for codes again before diving into that, might already be throwing a new code for the exact issue.

EDIT: Also, wipe codes with the car already in drive (torque pro, or a handheld scanner to wipe codes) and see if it drives normally and see what comes back.