PCM Replacement

I know many people will have come up with good solutions for this so I would like the benefit of your experience and advice. I am the proud (and awed, it is SO quick with so much torque!) owner of a 996T, 2004 with PCM2 and Bose. It has a Nav TV iPod connector which needs a software update, so will have to be taken out and connected to my PC. (Are there any easy to follow instructions for removing the trim and PCM?) I don't think the hands free phone system of having to use another sim is going to work for me and the navigation is not the best I've ever seen. So perhaps rather than spending money on installing a Denison gateway for the phone, I should look at replacing the whole PCM with a new double din unit. If I do that can you tell me: 1. Will a 3rd party unit fit exactly? 2. Do you have a recommendation for a make and model? 3. Will they all work with the Bose sound system? Thanks in advance. Andrew

Any reason why this wouldn't fit and work? http://www.sony.co.uk/product/in-car-navigation/xnv-l77bt

Hi Andrew, I also have a 2004 996TT. I had the Bose and the PCM2 with the MOST fibre backbone. I have removed the PCM2 and replaced it with a Pioneer double din bluetooth/USB/DVD haed unit. It doesn't fit straight in, you need the Connects2 fascia kit (about £36). The kit says it doesn't work with the cup holder, but if you fit it upside down it works fine and looks fine too. You also need a new wiring loom as you're bypassing the old fibre backbone. You'll have to modify your new wiring loom slightly too. Don't be scared of this though - it's not a deal breaker! I kept the Bose speakers and sub, but you have no choice but to replace the Bose (fibre) amp with an aftermarket one - I have a JL. The other thing you lose is the CD changer as this is fibre based too. The good news is you can fit your new amp where the old changer was, thus creating more space in your boot. I did look at the Sony, but doscounted it because Sony don't offer support anymore - it's web based only. Pioneer and Alpine seem to be the only companies left who actually have humans you can talk to! (and this is very valuable when doing a fibre to copper conversion!). If you're at the Silverstone Classic or Highcliffe Castle Concours this year I'll happily show you my install. Cheers, Neil.

Thanks Neil. Somehow I just knew it wasn't going to be straight forward. It all sounds pretty complicated - is this really the only way? I had hoped it was going to be a simple case of switching one head unit for another. Which head unit did you get? Did you fit it all yourself or get it fitted? Who supplies the Connects2 fascia kit and wiring loom? Which JL amp are you using? I spoke to Sony technical help this morning - so there is support on the phone.

If I use one of these wiring adapters, will I still need to replace the wiring loom and the existing amplifier: Item Description: Wiring Harness Adaptor suitable for the following Vehicles: Porsche 911 (Oct 1997 onwards) Porsche Boxter (Jan 1997 onwards) This adaptor is required to replace factory fitted radio with an aftermarket headunit (Alpine, Pioneer, Kenwood, Sony, JVC etc.). It will convert the car original power and speakers wiring connector to a standard ISO connector. Simply plug one end of the adaptor into your cars wiring harness, and the other end into your new radio, without the need of tools or cutting of wires. Harness adaptors connect the head unit to the original radio connector without the need to cut any of the existing wiring. http://www.dynamicsounds.co.uk/autoleads-pc9408-porsche-boxter-with-bose-system-wiring-harness-adaptor-p-2934.html

That adapter is only suitable for the pre-MOST cars, with the Harman amplifier, or the Bose analog amplifier, which was only used for MY2002. It is no good for a MOST equipped car. The Bose MOST amp only has fibre optic connections for the audio input, so it is impossible to link it to the line outputs of an aftermarket unit. As Neil says, if you want to replace PCM2, you have to either replace the amplifier completely, or bypass it and wire direcly to the speakers. The other problem is that (IIRC) the Bose speakers are an odd impedance.

Thanks Richard, I though that solution was going to be too easy. Do you know what impedance the speakers are?

I have a feeling the main speakers are 2 ohm, but maybe Neil could confirm that. They are obviously compatible with his JL amp. I believe the subwoofer is 1 ohm, but can be converted to 2 ohm by wiring the two speakers in series, rather than parallel. (Or something like that). All a bit vague - sorry. You could easily remove one of the rear side speakers, and it should be written on it. That's the easiest to get out. That Sony unit looks great. I like the fact it has TomTom Live built in. Pricy though.

Sorry for the delay in replying - had a busy day yesterday! I got my kit from www.caraudiodirect.co.uk - no support, but cheap prices! If you used to fit big car stereos in your 1.2L Vauxhall Nova when you were a teenager, then you should be OK, but you'll need a couple of days to do it as there's a lot of fiddly wiring to do. The Connects2 fascia kit model number is CT23PO02. You'll also need something to support your headunit and hold it firmly in place - I have a piece of MDF cut to size. For the wiring loom, you'll have to check what Sony recommend for your unit. My headunit is a Pioneer AVHP4300DVD with the CDBTB200 bluetooth kit. An Autoleads PC2-95-4 loom did the job with some minor modifications - Pioneer tech support are recommended! Richard is spot on (as always) about the speakers. I went for the JL XD series amp which handles the Bose 2 ohm inputs and is very small in size. I have the 5 channel version which is connected to the four front speakers and the subwoofer. I've installed it where the CD Changer used to be to give more space in the boot. My headunit runs the rear speakers. Hence, all the standard speaker wires were no longer in the places I needed them and hence lots of fiddly wiring! If you're not worried about boot space, installing a 7 channel amp in the boot where the old Bose amp was would probably make this a much easier job for you. Cheers, Neil.

As a consequence of swapping out the PCM2 do you lose the functionality of the onboard computer readout, including navigation instructions?

I still have the usual on board updates such as temp, boost, fuel etc... I never used the sat nav in my PCM2 and have not added a sat nav with my Pioneer replacement, so Nav Instructions are not something I'm aware of.

Thanks Neil. I understand that the subwoofer is 1 ohm and that there aren't any manufacturers who can supply an amp that can be guaranteed to work at such low resistance for any length of time. Are you running the subwoofer off the JL amp which is specified to run into 2 ohms?

Buying the 6 channel version of the amp and bridging the 5th and 6th channels to drop the output to 1 ohm was a consideration. However, this isn't recommended as most amps overheat at 1 ohm and there's not much air circulation where the CD changer is mounted. As the amp is the more expensive component, I've gone with the 5 channel version and 2 ohms. I took the view that I could always upgrade the sub if necessary, however, no issues so far - sounds great!

After lots of research and advice, here's where I've got to: 1. Sony XNV-L77BT or Kenwood DNX-7260BT. 2. Phonocar 3-Way Passive Crossover x 2. 3. AUTOLEADS-PC2-95-4. 4. Alpine MRX-V60 amplifier. 5. Connects2 fascia plate. What do think?

It'll look and sound fantastic!!

I'm not sure you will need that Autoleads adapter, as you will be making connections between the new head unit and amplifier with phono leads. The loom in the car has an ISO connection for the power, but will be missing a switched ignition supply, as PCM2 doesn't have one. Therefore you might want to either fit another ISO plug to the loom, and add that connection, or make an adapter lead using an ISO plug and socket if you don't want to modify the loom. The reverse gear and antenna amplifier supply are also in that same plug, so you will need to separate them for the new head unit. Making an adapter lead might be a good option. The other thing you will need is the speed signal, which you can take fron one of the bridge plugs on the relay board. You can get a switched ignition supply from there also. If you want the connector pin assignments for the PCM2 head unit, wiring diagram, and relay board, drop me an email and I'll attach them to a reply.