Where is the parking brake wire located

I know this is a bit of a thread necro, but I came across it when installing my own A6 into a VY commodore over the weekend and fount this helpful, but also misleading, and so am posting for anyone who comes across it in future, as the Atoto head units seem to be fairly popular these days.

Índice Show

In-dash Video Tapping into the Parking Brake Wire
Stereo Touch Screen or Video Monitor
How to Connect
What color is the parking brake wire?
What is a park brake wire?
Where is the parking brake switch located?

Like OP, I also bought the Aerpro fascia kit FP9056GK, which comes with a wiring harness that is intended to be plugged into a patch lead and the Aerpro SWC module. You don't need the module at all to get the steering wheel controls working in a VY. (And I assume VZ).

Grab the Aerpro harness out of the box, throw away the SWC module. I would say buy just the harness from SCA or wherever, but you want the radio plug and the fascia/bracket anyway, so you'll just have to take the hit on buying an extra piece you don't need.
Go to Jaycar and get a 12 Pin MULTI Pin Plug / Socket and a 6 Pin MULTI Pin Plug / Socket. Grab a crimping tool and some wire strippers while you're there if you don't have them already.
Terminate every wire on the Atoto harness and make up your two plugs. (You should probably tape up or cut off the 3.5mm socket as per OP, but I forgot).
Take the Aerpro harness and cut off every wire at the head unit end. NOT the car end!. Don't cut the black earth wire that connects two pins at the car harness end.
Throw away the wire & connector that plugs into the SWC module
Terminate every wire from the Aerpro harness, making sure that your plug matches up to the Atoto plug you made. You'll notice that the Atoto plug you made uses more pins than the Aerpro plug you made – that's cool, just match them up. If you have trouble matching colours, the top of your Blaupunkt head unit should have a sticker showing which pin is which.
Plug in, temp fit, and make sure you don't short anything out and blow a fuse (fuses under dash are worth checking if you don't get power up).

For extra credit:
Terminate a wire and fit it to the Aerpro plug you made. Run that wire to the park brake switch as per OP's solution, unless you want it to be able to play movies while driving illegal. Incidentally, the A6 allows you to turn off the prohibition on watching movies while not parked as a software setting, even if you have made the connection.

If you don't have a Calais model like OP, the area under the plastic clip at the top of the dash (where you undid the 4 screws to take the trim off) is an ideal location for GPS & WiFi antenna for a professional/invisible finish.

Contents

In-dash Video Tapping into the Parking Brake Wire
Stereo Touch Screen or Video Monitor
How to Connect

Your stereo system can be grounded with the parking brake wire. It will enable you to watch videos, enjoy a seamless Bluetooth connection, and many other features. Working in the auto industry before I have connected many parking brake wires and have dealt with many car brands so I feel like I can give you a detailed guide on the subject.

Generally, connecting the parking brake wire to the stereo system is not hard.

Examine the harness of the stereo system and locate the green wire (ground).
Cut the wire and strip its terminal (the insulation coating) with a stripper.
Obtain a good length of connection wire and strip the insulation to about ½ inch – both ends. Go ahead and wind the two naked terminals together.
Now thread the wire through the dashboard‘s middle section to the parking brake wire. Strip the insulation coating of the brake wire and wind the two wires together.
Secure the twisted terminal into a wire cap.
Finally, test your stereo system.

Before we kick off, keep in mind that bypass wiring is different from what we are going to learn. Bypass is basically for the touchscreen stereo systems where you can watch films. Our objective will be to wire the parking brake wire to the stereo system.

In-dash Video Tapping into the Parking Brake Wire

You are required to connect a wire to the parking brake wire if your stereo system is equipped with a video monitor or a touchscreen. The wire will serve as a switch that toggles the video monitor after the engagement of the parking brake.

The switch wire (connected to the parking brake) is found in varying locations in vehicles. The brand and model of the car determine the location of the switch wire. However, in general, the wire is often located near the parking brake.

Some vehicles have hand brakes between the front seats. In that case, you will have to move the center console to reach the wire. If your vehicle has a foot-pedal parking brake, run the stereo wire to the pedal under the dash.

Stereo Touch Screen or Video Monitor

The stereo touch screen (video monitor) is located on the car’s dashboard. The touch screen interface showcases all the information you require at a glance. You can easily and swiftly operate your stereo via the touchscreen receiver.

How to Connect

You will need the following tools to wire your parking brake to the stereo system:

Connecting wires
Pliers
A harness for the stereo system (comes with the stereo system)
Stripper
Wire caps
Adhesive tape

Procedure:

Cut a few feet of the stock wire depending on how far your parking brakes are from the stereo system. You can use pliers to do that.

Locate the green cable on the wire harness of the stereo and cut it. Using a wire stripper, remove the insulation coating of the wire cables to about ½ inch – the green cable from the harness, and the wire you just cut. (1)

Wind the two wires together and encapsulate the terminal in a wire cap. Twist the naked terminals of the two wires together and push the twisted end into the wire cap.

Thread the wire down the dashboard and into the parking brakes section. You can use a strap to immobilize the wire. Identify the parking brake wires. Join the terminals of the parking brake wire, and twist the cable that is connected to the green wire on the stereo system to the brake wire. You may use adhesive tape to secure the connection.

Testing the connection. You can now go back to the stereo system on the deck and test the Bluetooth, video, etc. (2)

Take a look at some of our related articles below.

How to check wiring harness with multimeter
How to cut wire without wire cutters
How to connect ground wires together

References
(1) insulation coating – https://www.sciencedirect.com/topics/engineering/
insulation-coating
(2) Bluetooth – https://electronics.howstuffworks.com/bluetooth.htm

Video Reference

What color is the parking brake wire?

light green wire which is the parking brake wire that comes with the Pioneer harness.

What is a park brake wire?

In road vehicles, the parking brake, also known as a handbrake or emergency brake (e-brake), is a mechanism used to keep the vehicle securely motionless when parked. Parking brakes often consist of a cable connected to two wheel brakes, which is then connected to a pulling mechanism.