Symphony II ISO Pinout colours


Registered User
Hi People

Recently bought a second hand A3 8P 55 plate, few issues which I'm looking to resolve, a few i have discovered relate to the stereo within the car.

When first bought after a day or so I've noticed the front speakers don't work at all, after using the filter and balance I've come to determine the rear speakers are showing to the stereo as the fronts, also upon turning the ignition on and after starting there was 3 pops that came from the rear speakers.

Upon purchase of the car the owner mentioned they had the radio upgraded to the new version, from what I can work out there is now a concert ii+.

I decided to remove the radio and check the wiring, its in a poor state. Who ever has fitted the unit has cut the iso connectors off, there are lots of splices in wires, wires wrapped in electrical tape, worst of all spade connectors on the back of the concert unit.

So here I am sat with a wiring loom bodged to make this new unit work, I'm hoping somebody could maybe provide me a wiring diagram showing colours of wires corresponding to either there job of pinout if possible.

With this information hopefully I can solder in a new iso connector for a start then sorry about a converter harness to convert the iso correctly to quadblock which shouldn't be to difficult.

I should metion I believe the car came with the symphony ii unit.

Anybody who can help it would be great.



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VCDS Map User
The radio antenna also isn't fully compatible so you may experience degraded reception.

We can repair the wiring if you need this done for you, pm if of interest :)


Registered User
Yes I am aware of the radio antenna, this doesn't bother me as i have retrofitted the aux into the unit.

I can repair it, if some body is willing to provide the information i require to rewire a new ISO connector into the car. Hopefully someone will kindly share the information.


Registered User
After studying current flow diagrams on elsawin I have managed to resolve my issue.

For anyone finding themselves in my situation in future I'll share the relevant information.

This applys to my late 2005, non Bose with rear amplified speakers. There are 2 wires I haven't worked out, one is K-Line which is superseded by canbus, the other being alarm ground. I'm sure I can figure these out when I have the volt meter.

Power: Red/white 1.5
Ground: Brown 2.5
FL+ Red 1.0
FL- Brown/Red 1.0
FR+ Grey 1.0
FR- Brown/Grey 1.0
RL Line Green 0.35
RR Line Yellow 0.35
Line GND Grey 0.35
Amp+ White 0.35
Canbus-H Orange/Purple 0.35
Canbus-L Orange/Brown 0.35