Ugh, the tail lamp sensor was being a little bitch on the Nissan.
Burned a bulb in the CHMSL. While you can buy bulbs that fit through the holes into the housing, or you can buy bulbs with the correct wattage rating, you can't get bulbs that fit through the hole and are the correct wattage rating (unless you go to Nissan and pay $20/bulb for 'em). So, if you get the bulbs that fit through the holes, the sensor lights up the indicator on the dash that a stop lamp has gone fucky.
I read the wiring diagram, and then completely failed to follow it, and snipped the wrong wire (I had intended to just snip the one that lit the dash lamp, but missed and got the other yellow w/red stripe, which was the running lamp illumination +12V. So, I ended up cutting the plug and sensor off entirely, and just wiring the lamps up directly to their respective 12V sources.
It's just as well, I have a load of LED lamps to put in that would have confused the shit out of it anyhow.
For some reason, there's a spare +12V from the brake pedal switch that I have no idea the purpose of, but I tied it back and made sure everything worked (running lamps, parking lamps, license plate lamps, reverse lamps).