I installed a z110bt yesterday, and while driving at night with it for the first time, I noticed the trip computer backlight wasn't on. (I drive a 2003 Toyota 4Runner, Sport Edition V8, no DRL). Also, the dimmer adjuster just to the left of my steering column no longer does anything. And what's even more weird, when I turned OFF my headlights, the trip computer backlight came ON! So this is pretty much just backwards.

The avic works fine; headlights on, it goes to night mode, headlights off, it goes to day mode. I hooked up the orange/white ILL wire to the dimmer wire, and the orange/black ILL Gnd wire to ground.

Any ideas?

Did you hook up the ILL wire to dimmer or illumination? Pretty sure you need to hook it up to a true undimmed "parking light" wire. If the factory plug only has dimmer, then you may need to run it to the parking light wire. If you find an alarm install guide for your truck it should have the color and location. Hope that helps. Careful, cause you can fry your dimmer circuit if it hooks up incorrectly.