So this car (R52 S) came with the HK sound system, but last year I ditched the head unit in favor of one with Android Auto and a screen for my backup camera.

Now, exploring deeper, I discovered that someone before me replaced all the HK speakers with Alpine components. I don't like them, but I own plenty of speakers that I do love - and picked up a compact 5-channel amp to facilitate a complete gut-and-replace, biamping and converting the rears into subwoofer duty..
But after unplugging the factory amp - man, this harness has a ton of wires! Not to age myself, but I remember GM and BMW and I think some Jeep m models back in the day that required a special harness to retain the factory head unit when replacing... what a stupid pain that was. This isn't a head unit of course, but with so many wires and pins in this harness, so I'm concerned of something similar.​
Are there any that relate to non-audio things, wires I may need to connect elsewhere (or pick up an adapter) to retain any non-audio car functionality?

I'm working on installing this amp rack, where I'm trying to repurpose the factory HK amp rack to accommodate this 5 channel compact amp-



My real question is this:
You can see in the photo that the factory HK amp rack harness is currently sitting in the amp rack space. I'm not sure where I'm going to park it or secure it yet, but my hope is that I can leave this completely disconnected, since there's nothing left of the HK system...
...but look at how many wires it has:


Can anyone confirm that the rest of my car will be fine with the HK harness simply unplugged? I'll wrap it and tape it to preserve it should I ever want to restore back to stock.

Thanks in advance to anyone who can confirm!

 

Sadly I can’t help but I might be in the market for a new stock head unit…

 

Shoot me a message - I hadn't thought about selling it, I've had the mindset of "keep it restorable" but I don't necessarily need the stock HK head unit so I'd think about selling it, sure.

 

It looks like from the amp harness wire diagram that there are truly only audio connections in here (I'm hoping this is the "black plug" info, I see there's also a "grey plug" variant that I don't personally have):
https://margaretandian.com/wp-conten...onnections.pdf
I'll couple it with this image to help any future people with the pin locations:


There is an exhaust temperature sensor wire in that harness also - very odd - will keep my fingers crossed that I don't need that, but it is just one wire and worst case I could bypass the harness on that one.

 

I ended up using this harness in a different way.

Running wires into the doors is very difficult, because the harnesses running from the doors terminate in plug and socket connectors at the front fenders:


This plug and socket is very narrow as you can see. You can easily remove the bolt on this end and unplug the harness, but it's a narrow plug and socket.

There's only 3 options for getting speaker wire into the doors:

1. Drill holes in the plug, and corresponding socket, to allow wires to pass through. Its risky to drill since the consequences of drilling wrong are high, and even if it's successful, it would be tough to fit even an 18 gauge pair - and good luck if you want to biamp the mid and tweet and want to run two pair of wires.
2. Drill a new hole in the door and corresponding fender entry into the dash cavity, to use these to run the additional wires:
   
   The real problem here is that there's a void between
   
   You can see that boot that carries the harness to the plug - the plug itself is about a half inch beyond that plug, the exterior metal of the door jamb is yet another layer beyond. In theory this is "doable" if I could open the doors widely, disconnect the bar that stops the door from opening too far, and had a straight drill shot at the door jamb and door. However, I don't have room in this garage space to experiment with that (especially with my battery disconnected and interior out), and that may not even be possible.
3. I could use the factory door wire that goes to the mid and tweeter, which are accessible from this harness. This is the option I took.

I am a fan of not cutting factory wiring. Keep things reversible. It wouldn't have been difficult to install taps that clamp on and pierce the wire insulators (T-taps), but although those are reversible, those are questionable for integrity reasons, and connection quality reasons.

Since I own a 3D printer, and already feels odd to leave a factory harness plug completely disconnected - why not use it?

I decided to make a 2 part, somewhat primitive connector to interface with the factory harness socket. First I found and purchased pins that would fit the socket connectors.

Part one was a plate with square holes that match the orientation of the factory harness. This was tough to print because there is less than a mm of plastic in this grid. Also I built in two outriggers designed to clip over the factory harness to hold it securely:

Part two was really just a rectangle that wraps around, and has those rounded indents to clip to the plate securely:

Part Three was actually a liquid rubber substance used as a potting compound to hold the plug and pins together...
I used Shoe Goo as it's less viscous than E6000 or even Goop. Epoxy could also work, but I like the vibration resistance of a substance like this. So odd choice, but it works:

And - it worked great.


It actually clipped securely, but I thought I'd still also secure it further with a zip tie, if only that my print orientation was such that the print layer lines were parallel with the surface, which isn't great for strength of the clip arms - even though I printed with high heat ASA filament and annealed that plate part of the plug specifically. No harm in securing things:

You see the other end of my harness has ferrules, for a secure connection at the terminal block I installed on the amp rack - which is a reuse of the factory amp rack in this space.

So with this solution, the biggest limitation is that factory wiring is only 20 gauge or 22 gauge until I'm inside the door. Not terrible, these are midrange and tweeter drivers.

I was able to run 12 gauge wires to the rear locations, where I've made some massive modifications to fit some absolutely giant 6.5” midbass drivers that use XBL² technology that I used back in my loudspeaker engineering days - so they'll even play down to 40 hz. Shouldn't be wishing for a subwoofer when I'm done.

 

Accidental duplicate post - deleted.

 

I ran 4 new wires into the door through the rubber piece. It was a big PITA, but doable if you have time, patience and lube.