TimInNOVA

After scouring Audi forums for clues on how to get a wire though the firewall of our D4 A8’s and finding nothing, I decide to create simple write up of how I did it while installing a Beltronics STiR+ in my 2012 A8. I live in a state where detectors are not allowed, hence I chose this unit because it cannot be detected, and it’s a hidden installation. The whole install took about 5 hours; most of that time was spent finding a path through the firewall.

I first lifted the panel covering the firewall on the drivers-side (left side). I could see a large wire bundle going through an oval shaped grommet (sorry, the picture is not great).

Next I removed the panel covering the lower half of the dashboard under the steering wheel; I spent some time using my fingers to feel for a large bundle of wire and grommet. I found it high above the dead pedal. I poked a coat hanger through and got lucky. I then used the coat hanger to pull the main wire from the head unit through and into the cabin. From that point on it got easy. I tapped power from the OBD-II connector (blue/red = switched power, brown/yellow = ground).

I ran the cable for the GPS antenna along the door sills and laid the antenna on the rear parcel shelf. I may later try and install it under the shelf, but for now this is working fine.

I hope this helps others out there contemplating this job. Good Luck.

Garycw

Nice post. Luckily the passport 9500 was already installed when purchased. After looking at all the parts involved, it would've been more than I dared tackle. My control pad is mounted on console and display unit mounted top of steering column. It was diffidently a professional install I wouldn't attempt.

Jack88

Good work. Whenever you need to get through the firewall, driver's side footwell is always the first place to look. If you have a passenger side, that can work as well.

diamondmit

...and, I used the switched wire going to the Obd-2 port. Much appreciated. Dd

mielke804@gmail.com

Hey 👋🏻 I’m doing this right now and am wondering how you got the wire through? I’m thinking about wrapping the wire to the hanger and pushing it through. Thanks

A8L_New_England

.

.

diamondmit

It's been a long time but your method is the right way. There are 2 potential pathways through the firewall and you should be able to feel your way through the larger of the two. My recollection is that there is a wire bundle going through there now, so make sure you wrap the tip of the hanger so it doesn't slice anything. Once you're through, it will seem pretty easy and straightforward to do again, should you ever need. Good luck!