I've had my interior out for cleaning and repairing the headliner, still have the rear door taken apart and subwoofer out. The radio head unit shows the headphones symbol meaning the rear "headphone" audio is turned on, but I don't have the Headphone controls. The place where it goes on the rear bins by the seat belts has factory covers.

Does anyone know if disconnecting the subwoofer turns on this mode? Is there a way to turn it off from the head unit since I don't have the remote?

 

Plugging in the subwoofer again does not turn it off.

The In-car Entertainment manual gives a temporary solution, but that only works until you turn the radio/car off.

NOTE: To override the drop in bass response,
press and hold the on/off volume control on the
main audio unit.

 

The signal wires all go through Header C0296. I disconnected that to split the system and the radio still thinks that the headphones are plugged in. I guess I'll be taking the interior back out to chase signal wires up to the front..

 

It looks like something internal to my radio or the software is just stuck telling it the headphones (that have never been installed) are plugged in. I've unplugged all the connectors on the back of the radio except power..

Is there a way to reset the radio?