My car's harness (02 CLK55, comand 2.0) doesn't supply illumination so the common practice is to tap into the wire that illuminates the cigarette lighter - it's +12V when the lights are on.  It was working, now it's not.  I only changed it once, so I don't recall exactly, but I'm certain that on the picture adjustment > dimmer page the icon changed from sun to something else (moon?) when the headlights were on, switching between day/night settings based on the voltage on the illumination wire.  I pulled the HU and checked the voltage - it's still +12V when the lights are on, 0V when off.

Am I missing something?   Is there some diagnostic mode I can kick the thing into?    

Mark. From the systems setting menu, scroll down to "picture adjustment". It has the dimmer settings for both daytime and nighttime. To adjust the nighttime dimming level, be sure to turn your lights or 12 volt source on. You did remember correctly, you'll see a moon symbol for the nighttime adjustment and a sun symbol for daytime. You'll only see the nighttime dimming adjustment when the 12 volt source is on.

Hope this helps.

I'm still having this problem - I have to turn the display off at night because it's so bright.   As I wrote last year, it was going into night mode when the lights were on, then it stopped working. At some point it was working again for a short time  I've got the dimmer wire tapped to the cigarette lighter illumination +12V, so I know it's getting +12V when the lights are on because I see the cigarette lighter illumination. The firmware has been upgraded a couple of times, so in addition to new software, it's been reset at least twice.  Anyone else have this issue?

I'm reluctant to pull the unit and send to the black hole nightmare that is pioneer warranty support, but I guess I might have to.   I might buy a cheap unit to tide me over ... I don't know if I can live a hole in the dash and no tunes ...

Check this video out to test your connection for illumination wire.

http://youtu.be/tw1Bo6R2wkU?t=5m50s

If your illumination wire is not changing the AVIC unit, then test your wiring to the AVIC. Don't just test the power outlet plug in your car, but all the way up to the plug on the AVIC unit. 

KOT

Check this video out to test your connection for illumination wire.

 

http://youtu.be/tw1Bo6R2wkU?t=5m50s

 

If your illumination wire is not changing the AVIC unit, then test your wiring to the AVIC. Don't just test the power outlet plug in your car, but all the way up to the plug on the AVIC unit. 

 

KOT

um, thats for the 7000.  I do not think there is a connection setting for the 6000

I was wrong, I found the connection setting and the dimmer. just in a different spot than the video shows.