I am wondering if it is necessary to connect the illumination wire on the AVIC Z110BT? I don't use the factory dimmer at all at night. My lights are always left on full brightness. Iam aware where to connect the wire...(HVAC: last wire/tan wire on the right side) just figured why do it if I don't ever plan on dimming my lights OR will the head unit automatically dim itself by being connected to this wire? Not sure if the vette has a sensor tied into the wire that is light sensitive and dims the components all on their own.

 

With the wire hooked up, it will dim the head unit display brightness anytime the headlights are on. My Kenwood 7100 display is actually too bright at night to drive comfortably so I made sure to go back and hook up the wire.
If the display brightness at night doesn't bother you then you have no worry leaving it disconnected, but be aware the head unit will not dim on its own.

 

You don't have to hook it up, but it is nice to have the HU dim at night.

It appears the z110bt needs to be connected to a wire that's hot when the headlights are on, not to a normal illumination wire. Check out this thread.

 

Ok so it does appear that it does function on its own at night...Ok cool thanks and I'll hook it up to that tanish or yellow colored wire on the right side of the HVAC. It's hard to tell what the color is, but the picture is the same. The same picture with the red dot on the wire lol.

 

I recently got my Z110T installed too. I'm opening mine back up right now to do this wiring. I didn't think it'd be too bright at night, but it's dark when I drive to work in the mornings and boy this thing is pretty damn bright. So I'll go ahead and hook into a wire.

Now, where do I find that wire on a C6?

Edit: Found out on the C6 where I needed to tap to get into night mode / reduced brightness. From another thread I read you have to tap into the gray/black wire on the traction control line.

 

After 1 week experience with my Z3 regarding this issue.

Lets all make sure what the intent of this discussion is:
to send a signal to the HU that it is dark outside and to POSSIBLY dim the screen so as not give you a sunburn at night (and blind you at the same time).

That being said: on my Z3, I tapped into the signal for the low beam headlights (at the steering column harness connector) into the Z3.

On the Z3, there is a menu that you can select for this item:
Option 1 - leave unit in day time mode (full brightness regardless of signal from my low beam headlights)
Option 2 - Automatic mode: without low beam headlight signal - unit is full brightness, with low beam headlight signal - the unit changes brightness but also color scheme to reduce light intensity (so you can see and not kill yourself running off the road at night).

The only fault to the above logic that I don't like is:
When you go to high beams, the low beam signal is gone and the unit returns to daylight mode.
That being said: I would much rather see the signal come from the parking lights (not day time running lights), so to keep it simple: If I had to do it over again, I would tap into the rear parking light circuit or in the HVAC harness if that serves the same purpose.

I assume the Z110T has the same internal logic above, but you would have to verify, then apply your tap in circuit location accordingly.

Andy