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Swapping Radio After Previous Owner Butchered the wiring.
Posted: Sat Jan 16, 2021 4:56 pm
by asward
Hello.
I was hoping to spend my Saturday swapping over the radio in my 318i.
This started with removing the Blaupunkt Porto 26 (Looks basically Identical to the
Stockholm R 26 without the LD button.
Once that was out I notice one thing. the previous owner must have been Edward Scissorhands, as all the cables had been chopped and changed and re-attached. I am looking to swap in a Continental TRD7412UB-OR, which seems to have quite a different connection profile.
These are the cables I have available to me, coming out of the loom (they were originally connected to the Blaupunkt Porto 26).
From L -> R::
White cable: Antenna Switch I believe. Fits to the terminal next to the +ve and Ground terminal.
Brown+Red Pair: Ground and +ve cables
Black+Red(x2): These are Left and Right speaker cables.
Black(With Electrical tape): FM Radio Cable.
I am also going to install the DAB antenna but that seems like a non-issue compared to actually getting the new radio connected. I understand that the radio antenna goes into the antenna socket, but seeing as I only have one L+R cable, and the new radio has LF,LR,RF,RR connections, so I am unsure what to do. I am confused as to where the white cable should end up, as I am assuming that controls the aerial extension.
If anyone could help me work out what it is I need to do to get the Continental connected, it would be greatly appreciated.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Sat Jan 16, 2021 4:57 pm
by asward
Here is an Imgur Link to some additional images:
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Sun Jan 17, 2021 8:04 pm
by Brianmoooore
None of the cables in your pic., apart from possibly the white (and red?) to the antenna motor are original E30, and that antenna cable joint will lose a lot of signal. It's a coaxial cable, and any joins made must maintain the coaxial arrangement.
The original E30 radio loom consists of four wires (brown, red/green, purple/white and grey/red). The speaker wires come in various colours, but are always tightly twisted pairs of the same colour, with one of the pair having a black stripe.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Mon Jan 18, 2021 9:30 am
by asward
Yes I thought it was strange how nearly every single tutorial on YouTube I could find had very different wiring. Looks like I've got a bit of a challenge on my hands.
I always noticed a small drop in radio signal whenever I went over speed bumps a bit too enthusiastically, or when shutting the door. so I guess this wiring explains it.
In terms of making this 'future proof'(lol), the best step would be to get these wires hooked up into a standard E30 format I would think. Are there any E30 harnesses out there?
Also. would you expect there to be a proper original loom somewhere in the dash I can source the original wires from? I could not locate any of the wire colours you mentioned, besides what are in a bundle which I believe are connected to the instrument display.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Mon Jan 18, 2021 11:12 am
by Brianmoooore
A radio wasn't a standard fitment on an E30, so any wiring for one was fitted by the supplying dealer. It was rare for a car to be delivered to the customer without one, but such cars do exist.
There' a multiple way socket behind the LH side of the glove box, known as the accessories socket. This socket is divided into sections, and one four pin area is for the radio, where the radio loom may or may not still be plugged in, if it was ever fitted.
There was no standard connector for radios at the time, so the loom was just bare wires at the radio end, however, there are aftermarket looms available now, on ebay, etc., with a plug that fits the accessories socket at one end and an ISO radio plug on the other.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Mon Jan 18, 2021 5:54 pm
by asward
Ahh okay. Thank you for your help. I have now located the accessory socket, and found 3 of the cables (the red wire that is joined to the white, and the red and brown 12v/GND wires) Pins V, X and W in the Accessory Socket JPG in the wiki.
The speaker cables seem to be going towards each side of the car.
I have been unable to find any aftermarket looms that look like they will fit into the socket unfortunately, the all seem to look like this:
https://www.ebay.co.uk/itm/Bmw-E46-E30- ... xySFJSDHTt
Do you know anywhere I could look to find something that I will need, as eBay seems to be coming up short on this one.

Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Mon Jan 18, 2021 6:53 pm
by Brianmoooore
You're right, I can't see any on ebay or anywhere else. There were plenty available not very long ago.
It looks like you already have an aftermarket plug, which explains the wrong colour wires.
To be fair, your existing wiring looks fine (antenna lead excepted), apart from those choc. block connectors, which I can't really see why they are there - every one of them seems to join a wire to an identical wire.
The other problem is that there is only wiring for two speakers. E30s normally have four.
If you cut those wires at the choc. blocks, and connect the correct plug for your radio, using soldered joints insulated with heat shrink sleeving, you'll end up with a loom to BMW approved standards.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Mon Jan 18, 2021 9:23 pm
by Contours
Looks like the W pin is missing from your plug in the picture. This pin is for the illumination wire and if it were present it would dim the radio display when you turn on the lights.
Position V is permanent live for the radio memory,--fuse 21
Position X is ignition switched live-----------------fuse 12
Position Y is your radio ground
You should be able to connect these to your new radio wiring as I wouldn't imagine a plug was available. This is a very neat way of connecting the radio which saves butchering into other wiring behind the dash.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Mon Jan 18, 2021 9:29 pm
by Brianmoooore
Some very late E30s also had a light blue wire to the radio from the green socket on the instrument cluster. This is a road speed signal, used to increase the radio volume slightly with speed, if the radio was so equipped.
Re: Swapping Radio After Previous Owner Butchered the wiring.
Posted: Wed Feb 10, 2021 4:36 pm
by asward
Hello again!
Been a while since I responded to this. I actually managed to make a wiring harness so I now have ISO connectors fitted to the car.
Thank you both for your help, yourselves and the Wiki were super helpful!
Here are some images in case you are interested! I think it looks nice!