So I have an AVIC z1, and I have put it in my envoy. On the GMOS-04 there is an illumination wire and a dimmer wire. I have hooked both up separately to the AVIC z1's illum wire and when I turn on the lights nothing happened.

Any thoughts?

Or maybe another wire easily to get to in the Envoy that would allow the unit to dim when the lights are turned on?

It seemed to work fine in my 05 camry, but no dice since I moved to the envoy

You should be connecting it to the illumination wire. Be sure to set the setting for 'auto dim' to 'on' in the AVIC menu.

It is set to Automatic and not day only

maybe their is a problem with the wiring in the harness from Metra, though everything else works fine

The ILL wire on the AVIC is only looking for 12v+ or 0v+. If the metra harness is not working, you can connect it to another location. You can connect it to anything that turns 'on' when the parking lights are turned on. You may see if your cig lighter has a light on it, or any other ambiant lights. There is also the light switch, or the parking light itself.

Cool, thanks

i had to use the orange white (dimmer) wire on the gmos-04 to get it to work.