Aftermarket radio installation A4 b6

[Steve Q]

To all those looking to install a new radio into their b6. Here is a little guide for you.
Firstly you will need to remove your radio to find out which system you have. There are two main configurations. Half amplified (rear) and fully amplified. Whether it is Bose or not doesn't really make any difference with wiring up.
If your car has a brown plug with four holes used then you have a half amplified system.
If you have no brown plug then it is fully amplified.
Don't be confused with the amount of harnesses available. There are only actually two. But different manufacturers and options make it seem like there are loads.
Basically if you have a half amplified system you will need Autoleads PC9-401/ PC9-404 or Connects2 CT20AU09/CT20AU10
If you use either of the second options you will need to make sure your new radio has a set of pre outs (RCA connections)
If you have a fully amplified system then you will need Autoleads PC9-410 or Connects2 CT20AU11.
If you have a fully amplified system you will need a radio that has 2 sets of pre outs (RCA connections) on the back of it.
The main problems people come across when fitting their new radio are the radio not powering up. Poor radio reception and no sound.
Audi didn't make it that straight forward to install an aftermarket radio. Basically there is only a single permanent feed to the radio and then the radio senses when the ignition is on and switches internally.
When you add an aftermarket radio you have to put in a new ignition feed so that the radio turns on and off with the key. This can be done two ways 1. by using a piggyback/add a fuse (see pictures) or 2. an online fuse (see pictures)
Option 1 is the easiest. You can get a piggyback fuse from Amazon/eBay/Halfords. You will need one for a mini fuse. Basically it replaces the existing fuse and adds a line out for another accessory.
In the case of the b6, fuse number 19 (front fog lights) is an ignition feed. Take that fuse out and put it into the piggyback fuse on the closest space to the silver folks. Then put a 10amp fuse in the other space on the piggyback and place piggyback into the fuse box as shown in picture.
Option 2 is to connect a inline fuse to the feed to the back of the light switch but you have to solder it in so option 1 is easier.
You will then need a about a meter of electrical wire rated somewhere between 12 and 20 amps. Connect one end to the piggyback and then run it through the dash and out of the radio hole in the centre console.
Audi's have 2 aerials, both in the rear windows. There are two connectors on the radio one is a Fakra connector and the other is a standard aerial connector. (See pictures) Both aerials run through a booster in the car. When you fit an aftermarket radio the booster no longer works so you have to buy an aerial adaptor that is powered. You can either use a Fakra one or standard one. I used a standard one which is Autoleads PC5-90 for a Fakra one it would be  PC5-137.
With regards to no sound, this is because you need to send a signal to the factory amp to turn on. The new harness will have a blue wire coming from it. This needs to be connected to the blue and white wire of the new radio harness.
On the new radio harness you will have a red wire and a yellow wire. Red is ignition and yellow is permanent feed. The Audi wiring has the permanent feed in the wrong place so you need to swap the wires over but only the yellow wire coming from the radio to the red wire coming from the car. 
The red wire coming from the new radio then needs to be connected to the new wire that has been run from the fusebox.
The aerial booster and amplifier blue wires need to be connected together and then connected to the blue and white wire coming from the new radio.
This should then allow your new radio to work once everything is connected up.
The only thing that may be annoying is the radio will turn off as soon as you stop the engine and not when you take the key out like the standard one does.
There is a steering wheel module you can use that will create an ignition feed for you. It may also keep the turn off when key removed feature but not too sure on that. If you are happy to spend the extra money the connector is Connects2 CTSAD001.2 this is a plug and play harness.
I have attached pictures to help you all and hopefully I have covered the installation process enough. 

Matthew Hellard. 

[01Chris]

Hi, Im a little bit confused and was wondering if someone could advise me please, I’m changing my Symphony stereo for an Android 13 head unit. I’ve connected all the blue wires together, I’ve cut the red cable I piggy backed to fuse 19, I’ve cut both the red and yellow cables from the new stereo plug and joined the yellow to the red cable, now am I right in thinking the red cable joins the new red cable coming into the car? If so I’m a bit confused as to where the other end of yellow wire goes to? And also the red wire from the PC9-401 harness go to?

 

Sorry for all the questions, it’s just for some reason I can’t figure it out.

 

Best Wishes 

Chris