Interesting, I'm having the same problem. All Canadian cars has DRL and I tap the illumination wire to the dimmer wire but nothing happens.
When I checked for the illumination status under hardware info, it has "OFF" as status. Not really sure what that means.
I really hope the unit isn't defective or anything.
when I have time, I am going to connect it to the wire that leads to the cigarette lighter. I noticed that when I turn off my lights (which don't affect DRL's one single bit), the cigarette lighter "light" turns off. Opposite happens when I turn the lights on. The unit is looking for voltage (or current) and if it finds it, it will switch to night-mode.
I haven't had the time to fiddle with this yet, but hopefully, this will be the final road-block to having a completely functional Pioneer Head Unit.
Paul