This is a shout out to anyone who's worked with the wires connecting the ICC to the factory sub amp.

I am installing a 5 channel amp to run all the speakers and there's a few ways I could go with connecting it.
I figure the neatest option is picking up what connections I can from the factory sub amp. Should be able to get an amp power-on signal, and possibly the audio too (though unsure if it will be lowpass only).

This is a pic of the plug on the factory subwoofer amplifier in the boot.
The wires I know for sure are:
Dark blue: Subwoofer +ve
Light blue: Subwoofer -ve
Yellow / Silver x2: +12V
Black x2: -12V


Does anyone know exactly what the Yellow, Brown, Orange and White wires do?
I believe they are these 4 wires on the ICC:
line +ve,
line -ve,
amp control,
amp detect
- but which is which?

I figured I would be able to tell with a multimeter which of these wires was turning on the amp as it would be 12V. I was wrong. There's about 4V on a couple of the wires when the system is on, but not 12.

Question 2:
What is the purpose of the amp detect wire? Why does the ICC need to know there's a sub amp connected? Does it high pass all the speakers? (That would be impressive).

Seems maybe this isn't an area many people have looked at so I investigated further.
Did some testing with a multimeter, plugging in and unplugging the factory amp. There's some very strange stuff going on there.

I think the Yellow wire is the amp turn-on wire, and the brown is the amp detect for the ICC.
When the stereo is on the yellow wire has about 4V on it, and the brown wire gets earthed by the amp.
Why they use 4V and not 12V I don't know. It would have been very convenient to get my new amps turn-on signal from there rather than tapping some random accessory wire.

The way it all works is very strange.
If the radio is already on when you then connect the factory amp, the amp won't turn on. You have to turn the radio off and back on for the amp to turn on.


PS
The orange and white also have about 4V which I'm assuming is the audio signal.

Anyone got new insight on this?

yeah mate pm me an email address

Hello
I am having the same issue with a BA xr6 with Premium Sound.
I would like to replace the factory Amp and Sub with a aftermarket amp and sub and would like to use the existing wiring to the factory sub.

I was looking at running power directly from the battery and then using wires from the existing Plug to use as a trigger wire and also as the RCA inputs for the new amp.

Can I do this and what wires going the plug could I use
A. For the remote trigger
B. As inputs for the new amp ( and are they RCA or Normal Speaker )

Please help

I ran in to the same problem myself.


37A & 37B are run in parallel from a 20A fuse.
The two blacks are in parallel to earth.

168 & 167 are line in (I'm assuming).
173 is a detect line of some sort.
370SA is your control line / Accessory.

Isn't the ICC signal to factory amp encoded in some way?

If you dig around enough you can find posts of someone trying and getting very close to making a module to wire aftermarket amps to the factory ICC.
They couldn't do it in the end because of interference that wasn't just static noise.

I wish i could find the thread to back up my babbling otherwise it just sounds far-fetched and kinda crazy lol.

Sorry, i should have said that they were trying to harness the pre-out channels that the ICC uses.
I know an aftermarket amp can be wired using low level line converters.

In the FG I've been advised the wiring colours are:

2x Yellow: 12V
2x Black: Ground

White: 5V trigger
Orange: Amp detect for headunit

Yellow: Signal
Brown: Signal ground

The trick is that if the Orange sense wire doesn't receive the correct voltage at power up, the headunit assumes no amp and does not send anything.

I made a circuit based on a commercially available product to interface this with an aftermarket amp but couldn't get it to work.

Is it possible the factory sub is part of the CANBus system?

Would make sense as to why just sending the correct voltage to ICC on power up doesn't work.
No packet data means the ICC doesn't output to the amp.

I guess that's possible.
I'm told it's simpler though - a 680 ohm resistor.

you need a low current switch, to switch the remote feed off the factory feed, (ie a darlington pair feeding a relay) and from memory resistor between the remote and feedback wire
Its been about 2 years since i got it working on my FG,
the factory amp does some processing with the audio signal, and the signal is quite low so your aftermarket amp gains need to be set higher

I'm using the rear speaker line signal for my amp inputs which is working ok.

I like the idea of the amp on/off being tied to the headunit. At the moment I'm using Accessories circuit, but there's the odd occasion it annoys me. When the key is removed from the ignition the headunit keeps playing (till the door is opened) but the amp has turned off.

The circuit I tested was based on a diagram you supplied 66 coupe. Didn't use the same IC though.
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Wouldn't have thought the IC would make a difference. Unless it was an issue with the 680 ohm resistor not being precisely 680. Don't remember the tolerance but it's been a while since I gave up so might have another look this weekend.