This is a 2008 GX470 with navigation and the factory Aux plug. I've done a LOT of searching in the archives here and can't find anything that addresses my situation, though some things come close.

The audio is not recognizing the Aux input. Either when using the Mode button or when pushing the DVD-Aux button on the head unit. So far I have tried:

Replacing the Aux plug with a new one, since this seems to be the most common failure point. No joy.

Different aux cords with iPhone attached. I've tried it with the iPhone connected and playing something and with only the cord connected. No joy.

I tried "resetting" the Aux by turning the audio off when set on FM, turning off the car, then plugging in the iPhone into the Aux, turning on the car and turning on the audio (this was described by someone in the forums as working for them). No joy.

I tested both seat heaters to make sure they were working (someone had the seat heater plug plugged into the Aux by mistake). No joy.

Haven't tried yet:

Someone indicated something was unplugged on the head unit. I hadn't tried that, yet, since it involves tearing the console open.

Someone else had to have their head unit replaced. Sounds expensive.

I recently bought this vehicle and the Aux hasn't worked since I bought it. Note that the dash replacement service was done soon before it was traded in. It is possible that the tech screwed something up in the process of replacing the dash, but I have no way of knowing that.

Any suggestions?