Okay, this is a bit wierd so I hope someone has seen this and knows a solution.

2006 Ford F-350 with steering wheel audio controls, Avic D3, and of course the PAC SW-PS adapter.

Everything functions perfectly until I turn on the trucks lights and then I loose the volume control on the steering wheel. "Next" and "mode" functions continue to work just fine, but the volume control becomes MIA. Turn the lights off and all is well again.

I do have the illumination connected so the radio dims at night, but why the interference between the dimmer and steering wheel controls? Is this an issue with the PAC adapter or programing? Some weird Ford issue? Would it be best to avoid the factory dimmer wire and source this from the light switch instead?

Make sure that the swi is connected to ground and switched 12volts. for power. Cause it sounds like it might not be.

Oh yeah, it's only three wires on my truck. 12V, ground and the "white" wire on the interface. All connected and works fine until I turn the parking lights on. Then suddenly the volume controls don't function. I'm betting if I disconnect the dimmer line it will function 100%, but I was hoping someone has seen this issue and has another alternative. This just doesn't make much sense.