Could we be on the wrong track looking at the OEM DRL wiring? No DRL on a 2005 USM NSX, & it seems unlikely the aftermarket shop would bother wiring it per OEM wiring for DRL's, with fuses in the correct location, gauge cluster indicator, etc. And the operation sounds much simpler than the OEM DRL, which won't activate DRL if the emergency brake is initially on. [USER=25899]@Madhatter10-6[/USER] any E-brake effect? Gauge indicator? Operation at ignition I (Accessory)? Even less likely that an '05 has the wiring for the fog light look-a-like DRL's that came on '91-'01 NSX's shown in the pic in post 3.
It sounds like a relay triggered by the ignition-on 12V to either ground the headlight switch circuit or power the low beam circuits. They didn't just connect the headlights to the ignition power or the lights wouldn't work when the ignition is off, as they seem to. More likely grounding the supply side of the headlight relay, as they would have to tap into both the left and right headlight circuits and that would also be bypassing the fuses, so the taps would need to be fused as well. I expect it is like [USER=20407]@MaxGeek[/USER]'s setup. Pretty much need to trace out the headlight switch circuit, then follow the headlight circuit back to the fuse box/relays. There must be a tap-in in one of them. Starting with the ignition-on or accessory-on circuits would take forever.
At the risk of sounding glib, why bother removing this? It's arguably safer & I doubt it weighs very much. Here are shots of from the 2002 electrical manual for assistance, which I think should be similar to 2005, but I'd recommend grabbing one for yourself, since it also has great pictures of all of the electrical connectors to help you locate them.
[ATTACH=full]198630[/ATTACH][ATTACH=full]198631[/ATTACH]
[ATTACH=full]198632[/ATTACH][ATTACH=full]198633[/ATTACH]
[ATTACH=full]198634[/ATTACH][ATTACH=full]198635[/ATTACH]
Edit: Was thinking about this waiting for a luncheon at church when I thought, "How would I add DRL to a fixed headlight NSX?" There are +, acc+, Ign+ and ground spades just above the fusebox near the driver's door. I'd put a relay there, with the trigger wired to the ign+ & ground, and the switched leads connected to ground and run to red/blu, either at C416 (bottom of the steering column) or perhaps C243 (behind right kick panel.) See page 100-5 above.
