Sorry for the delay guys, work getting in the way.
Would you believe it, when googling around for reminders while writing I found
this from Volvo. Turns out they DO offer a kit for V70's that aren't prewired. I'm pretty sure this wasn't around last year (unless I missed it) but it would have made life a whole lot easier, although probably more expensive!
Apparently you can't do this on 08MY cars as the infotainment software doesn't support DAB at all, but I'm not aware of any other limitations - if you're 09-16MY then you're probably OK but don't take my word for that.
If you still want to go down the manual route, the main bits you'll need for this are:
- DAB Module: I used one from a 2012 V40 as it was the cheapest one I could find. At a guess probably most modules will work (regardless of part number) as they all communicate on the MOST bus but I may have just been lucky. If you can, get one with some loom still attached
like this one on eBay as it makes life easier when connecting the power etc.
- DAB antenna: Any decent quality DAB antenna should do but it must be amplified and have a Fakra connector to connect to the module.
Something like this should work. The "proper" way to do it is to replace one of the existing FM amplifier modules attached to the windows (varies depending on model) but I never found a suitable one on eBay so went for the easier, if slightly less "OEM" option.
- MOST 'Y' Cable: The MOST bus is a ring network of optical fibre so you can't just cut in to it (more's the pity!). I couldn't find a sensibly priced Y cable, so I made one out of a
loopback connector and a
male-to-male cable. It's difficult to explain (if it's not obvious!) what you need from the cable so I've attached a picture. Make sure the male-to-male cable is long enough to route between the sub and wherever you're fitting the module. Ideally the fibre should be routed down the side of the footwell with existing cables so it doesn't rub. I found 2 metres to be a little too tight. As it's fibre, you can gently coil up and secure any excess without it causing interference.
- Software: You'll need Infotainment Theft Prevention (ITP) Removal and DABM Application (30786292 and 31266811 for V70 2012 I believe). The first tells the car to re-audit the modules in the chain and accept what's present, the second provides the DAB functionality. They're about £20 each plus labour to load them. My local indy (Wrights of Attleborough) have VIDA and were a damn sight cheaper on labour than the franchise dealer (Holden Motors).
For V70's the module is mounted between the rear bench and the cargo area. If you have 4C then you should already have the correct mounting bracket in place and the module fits on top of the suspension control module with four bolts. If not you're probably best off securing it somewhere with heavy duty Velcro or similar.
The wiring diagrams show that the module is connected to a permanent 12V supply via a 5A fuse. There's usually a good supply for this somewhere close. If you don't have a module with existing loom then you can make one from Dupont connectors (not perfect but fit well and are safe). Pin 1 on the power connector is 12V and should be the left hand pin as you look at the module label up but check this for yourself obviously!
Once you have a suitable Y cable, the easiest place to connect it is probably the amplifier under the driver's seat. The cable is bright orange and pretty easy to find, but don't bend it too sharply as there's a risk of snapping the fibre. Unplug the cable from the amp, attach your Y cable then put plug 1 back in to the amp. It's worth pointing out here that you won't have any audio in the car unless you attach and power up the DAB module, or put a another loopback connector on plug 2 as the ring needs to be complete to work. There's nothing to stop you connecting and powering up the module - the car will just ignore it until the software has been downloaded.
The antenna needs to be powered from a switched supply so as not to drain your battery. At the moment I have mine connected to the 12V socket in the centre tunnel but this isn't ideal as the radio cuts out when you put the ignition on 1 rather than 2. I think the best bet on this one is to attach it to one of the existing aerial amplifiers in the roof lining as it looks like they have a 12V feed that's switched by the infotainment module, so will turn on/off at the right times. I haven't done this yet so don't know if it will work or not, but it should do.
Positioning the antenna is important too as reception quality seems to vary a lot depending on where it is. Once you have everything connected I'd suggest temporarily attaching the antenna with blu tac or something similar for a few days to see where it works best. The nearside rear window works well for me. I do get some dropouts in the signal but they seem to be only in blackspots or poor signal areas - not bad enough to worry about.
Volvo also mention a second antenna in the sharkfin on the roof, but this is only used for L band DAB which isn't used in the UK, so you can safely ignore it.
The aerial connector on the module is a dual Fakra-B (I think) and has two sockets (L band and VHF) but you'll only need to use the VHF one. The two sockets have a small piece of plastic joining them together which will need to be cut away if you don't have any loom to connect to. you should find that the connector will hold itself in place as they're quite snug but a bit of plastic tape works well if not. I can't remember offhand which is which but it's pretty easy to find out as you won't get any reception if you're plugged in to the wrong one!
As you're only using one connector, both the DAB and infotainment modules will probably log diagnostic codes to say that the other connector is open signal as they're expecting it to be connected to the sharkfin, but this doesn't cause any operational problems and unless you've got VIDA and DiCE you won't see them anyway.
It's a bit of a faff to fit everything as the headlining needs to come down a bit, which means taking trim off the side of the cargo area and I seemed to be constantly taking the rear seats down and back up again, but it's not difficult. I spread it over a weekend but it can easily be done in a day.
The modules should support both DAB and DAB+ so there shouldn't be any compatibility problems as/when stations upgrade.
There's also
this thread from a Norwegian forum that has more info about retrofitting and is very similar.
That's everything that I can think of at the moment. Suddenly it seems like a lot of effort to go just to listen to RadioX in the car! As DT19 mentioned, it's cheaper and easier to use an app on your phone and stream via Bluetooth, and may sound better too as a lot of DAB stations have really low bitrates and are mono, but I like to fiddle
Hope that helps somebody, let me know if I can give any more info!!