I've run into some trouble installing F700BT in my 2002 Saab 9-3 Viggen Convertible.

My car interfaces with the OEM radio's dimmer through a digital connection, so I had to tap into a dashboard light. I tapped into a light around my cigarette lighter, and I'm not seeing any dimming in the avic.

I tested the dimmer/illumination pin on the harness that plugs into the AVIC and found it was getting the power... 2V at lowest dim and about 11V at highest.

I'm wondering what is normal. My car can't have its headlights shut off so if the unit really only has a lights-on/lights-off mode, maybe I shouldn't expect to see anything. But if I should be seeing a smooth range of brightness as I adjust the dimmer, I guess something must be wrong.

How is the dimmer supposed to behave? Smooth adjustment or just "lights-on"/"lights-off?"

It is dim/bright with lights on/off, not progressive analogue dim as you may have expected.

I guess if I want to dim the screen without going through the menus I am going to have to hack my car to add a switch for lights-on/lights-off on the wire coming in to the AVIC illumination.

Or maybe there is some way I can get a relay or integrated circuit that will break the circuit if the voltage is less than 10V. So if my dash dimmer is fully bright, AVIC will be on one brightness; otherwise it'll be on the other brightness. But I have no idea if this is feasible or how I would do it. Any ideas?

Hmmm... or maybe I could get a photoswitch.