Join Date: Jan 2020
Location: San Jose, California, USA
It's been more than a year but I'll recall the best I can. I have a 2009 Speed 3.
In most articles I've read folks are sending the wires up the sides of the vehicle, along the door frames. I went along the top of the center channel, between the front seats. I removed the rear seat, left rear trim, and everything from the trunk. I ran the wires behind the rear bumper, to the right side of the vehicle where the was an existing set of wires that went through the floor to the trunk just behind the wheel arch. I then went around the wheel well to the left side of the trunk and through to the cabin next to the left rear seat. Then behind where your feet rest in the left rear seat to the center channel. Then it was under the carpet up the center channel to the center console, which is also where I connected to the reversing wire. Getting through the gap above the channel and under the carpet was very difficult. I had to buy some flexible probes to feed the wires through - one was made of fiberglass and the other a flat metal strip. Of course, I had removed the center console including around the gear stick because I was also replacing the head unit - which took the rear camera feed.
I sent all (3?) wires all the way from the rear bumper to the front of the vehicle because I couldn't find a positive wire in the rear where I was working.
Now I wish I had taken pictures.