I have a Kenwood headubit, it's been in for 4 years. I also don't have steering control etc.. but I used a Connects2 CTSVW002.2 adapter, with the Kenwood patch lead.
This is for retaining steering controls, but also get around battery drain issue (it did for me), and was cheaper and less hassle than updating the canbus with the benefit of it also being a harness for plug and play headubit install.