Porsche 911UK Forum

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

Replacing the PCM in a 997 with double din (non Bose)

matsmith749

Well-known member
Joined
13 Oct 2015
Messages
57
After reading so many threads regarding changing out the basic PCM system in my gen 1 997 (no steering wheel controls / standard non-BOSE), I finally got round to doing it today.

It's actually very very simple & not the madness electrical mashup that some of the threads will lead you to believe (at least for the standard non bose system).

Remove PCM system (instructions followed from YouTube video) - easy.

I installed a Pioneer AVIC F77 DAB (capacitive touchscreen / Bluetooth / NAV / all the bells & whistles).

You will need a cage & surround which again were easy to find from the t'interweb.

You will not need any conversion cables / MOST interface leads.

Unplug the 3 plugs from the back of the PCM, the 2 aerial connectors. Unplug the Fibre connector.

If you just plug the ISO connectors straight in the sockets on the back of the new stereo nothing will happen - there is no switched 12V to the socket.

This is the only tricky bit of the installation - run a fused red wire from an ignition switched spare fuse in the drivers footwell to the back of the stereo (not that tricky really - 15 minutes & sorted).

Connect that to the stereo in place of the switched 12V line (mine had split leads with bullet connectors for the power, so very simple to do).

Now connect it up - you will have sound but only from the 2 small front door speakers & the 2 rear speakers. It will sound ok but not great. Basicly you will be running with half the speakers in the car functional - the sound will be tinny & lacking bass if you leave it like this. New car stereos tend to have lots of tweaking options, so you might get it to sound ok, but really you need to enable the ASK amplifier to turn on all the other speakers to get decent sound.

The ASK amp gets it's input from the standard brown ISO socket which provides the speaker outputs from the stereo - it kindof mashes these up into the signal it needs for the big door speakers / centre channel etc. You don't need to provide extra speaker wiring to get these speakers to come to life, you just need to switch the ASK amplifier on :)

The ASK amplifier fitted in the standard 997 system is fed from the standard ISO speaker outs & is already receiving an input (no sound goes on the fibre connector, that is for communicating with the NAV unit & displaying the current station on the instrument cluster). It's getting the input - but not switched on (hence no sound from big speakers in the front doors / centre speaker).

To fire up the front mounted ASK amplifier, look at the ISO cable connecting your new stereo & identify the blue / white Antenna 12V cable (may be labelled remote). This needs to be fed to the black / red wire that is PIN2 of the black ISO plug (it will be in PIN5 as standard on the new ISO plug on your replacement stereo). This switches on the ASK amp when you turn on the radio.

You can just move the pin in your ISO connector (they just pull out with firm pressure) or run an extra wire with a bullet connector.

GPS & DAB antennas need to be located under the front plastic where the windscreen wipers are & get fed through the central rubber grommet to the rear of the stereo (again YouTube video for the location of this).

That's it - none of the original wiring needs to be changed or touched. You can switch straight back to the PCM system at any time without any modification if desired.

No real electrical shenanigans to worry about. No MOST boxes / complex interfaces to buy. It pretty much just plugs straight in using the existing ISO plugs from the PCM system.

1 12V switched wire to run / 1 pin to change on the ISO.

Sounds loads better (not touched the speakers remember), plus now has all the modern features.

Easy (assuming you are methodical & careful, respect you car electrics, are handy with basic tools. I took about 4 hours to do this, so not exactly a quick job).
 
matsmith749 said:
After reading so many threads regarding changing out the basic PCM system in my gen 1 997, I finally got round to doing it today.

It's actually very very simple & not the madness electrical mashup that some of the threads will lead you to believe (at least for the standard non bose system).

Remove PCM system (instructions followed from YouTube video) - easy.

I installed a Pioneer AVIC F77 DAB (capacitive touchscreen / Bluetooth / NAV / all the bells & whistles).

You will need a cage & surround which again were easy to find from the t'interweb.

You will not need any conversion cables / MOST interface leads.

Unplug the 3 plugs from the back of the PCM, the 2 aerial connectors. Unplug the Fibre connector.

If you just plug the ISO connectors straight in the sockets on the back of the new stereo nothing will happen - there is no switched 12V to the socket.

This is the only tricky bit of the installation - run a fused red wire from an ignition switched spare fuse in the drivers footwell to the back of the stereo (not that tricky really - 15 minutes & sorted).

Connect that to the stereo in place of the switched 12V line (mine had split leads with bullet connectors for the power, so very simple to do).

Now connect it up - you will have sound but only from the 2 small front door speakers & the 2 rear speakers. It will sound ok but not great.

The ASK amplifier fitted in the standard 997 system is fed from the standard ISO speaker outs & is already receiving an input (no sound goes on the fibre connector, that is for communicating with the NAV unit & displaying the current station on the instrument cluster).

To fire up the front mounted ASK amplifier, look at the ISO cable connecting your new stereo & identify the Antenna 12V cable (may be labelled remote). This needs to be fed to the PIN2 of the black ISO plug (it will be in PIN5 as standard). This switches on the ASK amp when you turn on the radio.

GPS & DAB antennas need to be located under the front plastic where the windscreen wipers are & get fed through the central rubber grommet to the rear of the stereo (again YouTube video for the location of this).

That's it.

No real electrical shenanigans to worry about. No MOST boxes / complex interfaces to buy. It pretty much just plugs straight in using the existing ISO plugs from the PCM system.

1 12V switched wire to run / 1 pin to change on the ISO.

Sounds loads better (not touched the speakers remember), plus now has all the modern features.

Easy.

Great write up Mat, I am glad it went smoothly for you, and very interesting you comments about how to power up the ASK amp to run the 2 big door speakers as I know some have had issues with that bit and not getting any bass.
Your 997 is clearly one of the ones that didn't have fibre optic cable as my non bose needed the most interface before it would work.
But good to get clear conformation that there are two types of wiring set ups for the PCM2.1 on the 997.1 ,initially I didn't buy a most as I had hoped mine was like yours, but no another £300 had to be spent on the optical interface :nooo: . where did you tuck the mic or did you manage to make the stock one in the steering column cover link ok. :thumb:
 
My car does have the fibre optic cable running to the PCM system - but the sound goes out via the brown ISO socket. I'm guessing that the fibre link is there to share data to the NAV unit / info to other systems etc.

My instrument cluster now shows ----- instead of the radio channel, this seems normal after switching out the PCM unit.

I installed the MIC for the new stereo on the plastic trim under the steering wheel at the edge where the trim meets the centre console. It angles up to point at the mouth. Tested it earlier & it works great - my missus could not tell I was in the car, so sound quality / echo reduction is spot on.

Matt
 
matsmith749 said:
My car does have the fibre optic cable running to the PCM system - but the sound goes out via the brown ISO socket. I'm guessing that the fibre link is there to share data to the NAV unit / info to other systems etc.

My instrument cluster now shows ----- instead of the radio channel, this seems normal after switching out the PCM unit.

I installed the MIC for the new stereo on the plastic trim under the steering wheel at the edge where the trim meets the centre console. It angles up to point at the mouth. Tested it earlier & it works great - my missus could not tell I was in the car, so sound quality / echo reduction is spot on.

Matt

Perfect mate, re the ------ on the instrument cluster I thought that was normal and had it for 18 months :? there's a very easy way to change round the info that is displayed there so you end up with no----- and two lines of info see your handbook I will also try and find the recent link to the fix that was on here . :thumb:
 
Phil - thanks for that - '------' now replaced with meaningful info :)

Only other things that I forgot to mention, the bezel that I got had to be trimmed slightly to allow the motorized front of the pioneer to open smoothly (5 minutes with a dremel, can't see it when installed).

Also in the fuse box, there are about half a dozen spare fuse locations that you can tap for a switched ignition 12V source.

The bottom row of the box has a couple of spare locations, these are ignition switched, but seem to stay on for a random time after the key comes out (maybe 30 seconds / maybe 5 minutes). The next row up switches off the instant you remove the key - much better.

(edited the first post to explain how the ASK amplifier works a bit better)

Matt
 
Glad you got ----- sorted mate, good heads up for others re the dremel for any motorised screens ,and the fuse box info :thumb: :grin:

I have some Porsche screen splash options if you need them PM me your email and I will send them to you. my favourite one is below
 

Attachments

  • splash_screen_417.jpg
    splash_screen_417.jpg
    7.7 KB · Views: 10,314
Matt, very interesting indeed and I will get my fitter to try it when I get back from Holiday (currently driving a peugot 308cc around Mallorca!)

Do you have the steering wheel controls? Thats the main reason I believe you need special lead (technical term!) I think?

cheers
 
Yep - mine is the standard 997 audio setup without steering wheel controls.

Always going to be the easiest I guess :)

Matt
 
Update time :)

I am all working :)

I have the connects2 lead to make the steering wheel controls work in as well, but the connection you said was needed to power the amp up is just the same, just put into the connector for on the lead, but bypassing the lead itself, and it all works nicely. Lots of Bass, sounds great.

So, the reason they use something like it to tell the amp to turn on is becuase they have just done it off what would of been, at some point in time, the linke from the head unit telling an electric aerial that the stereo was on, and the aerial needed to rise so it would work. Porsche seem to of used that functionality to instead tell the amp to turn on. There is literally no wire in the lead or in the connections without the lead and all it needs is a wire. Incredible it is that simple but makes perfect sense.

Nice work Matt, we should take everything about this, the head units that we've all used and have working and put in a sticky thread for future reference.
 
resigner great you got it fixed, Need to make sure the other guys having bass issues are all aware of the fix. Well done Matt :worship: great fix as resigner said it needs a sticky, as the replacement head unit mod and the attached issues come up so often on here. :thumb:
 
Well done :) It's surprising how easy it is to get sorted once you know what it is.

Matt
 
An old thread I know, but am just about to instal a new unit into a non Bose 997, it had pcm 2.1 with telephone, nav and cd changer if that makes any difference... does it matter which of the 2 Ariel leads you use for the new unit?
 
I don't know the PCM 2 system but I believe it does not have DAB (or associated aerial) so I assume the 2 'aerials" you mention are for GPS signal (for the sat nav) and FM (for the radio) :?:
 

New Threads

Forum statistics

Threads
124,357
Messages
1,439,484
Members
48,717
Latest member
Atlas.997
Back
Top