Ok…so we’ve pretty much determined it is a Bluetooth connection. The red wire coming off the steering wheel start/stop button is actually an antenna. I’m assuming there’s a matching one tucked in on the other side for the drive select switch.
The receiver on the other end plugs into the harness which interfaces with the center console start/stop button wiring harness. It’s the blue dongle. Under the heat shrink wrapping is a circuit board with the bluetooth module/receiver.
The harness which plugs into the module has a black ground, a red +12V power, a mystery blue and white wire and a slightly purple wire which I believe is the antenna.
The original, full harness contained an extra plug and three extra wires which didn’t seem to have any use in this application so I clipped it off.
This is the OE portion of the harness which plugs into the airbag’s main wiring harness as well as into the right side pod on the steering wheel. It gets completely replaced with the harness that comes with the new steering wheel.
Flipping the pod over, the stock OE harness plugs into the socket on the bottom left of the photo. You’ll remove the stock harness and plug in the steering wheel’s harness.
Now here’s where the main problem lies (one of several). The OE steering wheel harness is three wires with the fourth spot in the plug being a blank.
The new harness has four wires which are also spliced together with wires from both buttons so there’s no way to really remove them and being all black, no idea which one runs where. I have a feeling I’ll need to jump one of the terminals but I’m not 100% sure.
Moving to the center console start/stop button, I’ve used taps for three of the wires to make testing easier.
Power for the module comes from a 12V+ which you can take from the fuse box on the driver’s side. I’m using the right terminal, in between the 30A and 5A. The negative can be attached to one of the two studs in the center console.
When I apply power to the module, it’ll flash momentarily so I know it’s receiving power.
Here’s where it gets interesting. The following four photos are the “installation instructions”. Doesn’t really help, only invites more questions.
A fellow RS5 enthusiast came across what are essentially the same switches, sold separately from the wheel, which has a bit more in terms of actual installation instruction but again, it’s a four wire setup.
This is copied/pasted verbatim.
How to install?
R8 button installation instructions
The appearance and functions of the dual buttons on the QD-88X series steering wheel are described as follows:
This product is designed from the dual buttons of the R8 steering wheel. The buttons are divided into left and right sides. There are two logos. Red represents POWER, which means “one-button start” function, and is installed on the right side of the steering wheel; black represents SELECT, which means “driving mode selection” ”Function, installed on the left side of the steering wheel;
“One-key start” uses a silicone double-button detection mechanism, so when operating, you need to press the silicone switch to detect and then press the physical button for feedback to prevent misoperation during driving and play a double protective role; and The “driving mode selection” button is to directly press the physical button to give feedback, which provides a better user experience.
Another: working parameters and features of this product:
Rated working voltage: DC 12V;
Standby current: <3MA
Transmission method: 433Mhz
Original car wiring harness socket docking, wireless version, free of hairspring, free of welding wire, free of broken original car wiring harness
Key installation steps:
Loosen the airbag: start the car, turn the steering wheel 90 degrees to the left, insert a screwdriver into the small hole behind the steering wheel to pry the internal buckle of the airbag, then turn the steering wheel 90 degrees to the right, and use one from the other hole behind the steering wheel. Insert a screwdriver into the other internal buckle of the air bag, release the air bag, and pull out the connecting wire between the air bag and the multi-function button.
Remove the rubber frame between the bottom of the steering wheel and the airbag, use the fixed gasket in the product accessory to mark the button installation position, use an electric drill to drill the fixing screw hole and the threading hole, insert the wiring harness, and use the screw in the accessory package to connect the button and Lock the rubber frame, arrange the wiring harness between the two buttons, and install it on the bottom support of the steering wheel.
Restore the rubber frame with the buttons and the bottom support of the steering wheel to the car, connect the wiring harness between the airbag and the multi-function buttons, and then press the airbag back to its original position after checking. The steering wheel buttons are installed.
Installation steps of wireless receiving board:
First find the one-key start position of the original car, and disassemble the components surrounding the original one-key start-up. The purpose is to remove the original one-key start-up wiring harness.
Disassemble the gear handle, unscrew the screw and pull out the gear handle. Unscrew the decorative parts covering the surrounding area (the specific driving model is different); please confirm whether the screws are all loosened before disassembly.
Disassemble to the original car with one key to start the rear wiring harness, find the pin on the definition: 3&6, and connect the blue and white wiring harnesses on the wireless receiving board to each of them. 3&6 are not defined.
Connect the wire harness with the fuse to the power supply B+ (long power) fuse box, and connect the black branched wire harness to the ground wire (ground).
Note: The wireless module will flash slowly within 10 seconds after the power is connected, indicating that the power is connected!
After the above two steps are completed, the installation is basically completed, and you can perform test verification. The indicator light on the wireless board will flash back after receiving the button message!
Please note: Our R8 button is the easieat button to be installed. You only need to remove your airbag and install it directly to the steering wheel within minutes.
Only 2 plugs.One is to the airbag connector ,the other is to the multifuction steering wheel button connector.
Note: This is not original Audi VW parts. This wiring is simple. Just connect the switch signal wires. No need to replace the airbag. Safe and convenient. Suitable for car installation with start button and driving mode. If your car does not have a start button and a driving mode switch. This switch cannot be used.