How to add 12volt accessories.

[j3w]

I did some searching and I found a few leads but I didn't find a consensus.

I want to add an iSimple FM modulator to my 2004 S. I already removed the console and radio to connect everything up and modify the console to accept the unit's switch but I don't have any firm ideas where to get power from.

There are fuze boxes on both sides, of course and the cigarette lighter power outlets as well, so I am sure I can come up with something.

But, really, what is the best practice in this case?

[xmac]

The factory radio manual is a good starting point. For example, if you look on page 28 of the CDR220 manual, it shows 2 power wires you can use. Socket A, pin 4 shows a "Permanent positive" meaning power stays on with the ignition key out, the other one is Socket A pin 7 is a "Switched Positive" which only powers on when the key is in the accessory position or on.

I am not sure which radio you have but I hope that helps point you in the right direction.

[j3w]

I have a PCM 2.0 and I hadn't considered tapping into the radio's power circuit, that is diabolically clever.

Any hints as to where would I find a manual that includes a wiring diagram for such a thing?

[CeliaWessen]

Vehicles with PCM 2 and up will not have ACC power behind the head unit. It uses the CAN-BUS network to activate on ignition. You'll need a CAN-BUS adapter or a manual toggle switch.

[j3w]

Vehicles with PCM 2 and up will not have ACC power behind the head unit. It uses the CAN-BUS network to activate on ignition. You'll need a CAN-BUS adapter or a manual toggle switch.

Thanks for the heads up. The iPod thing I'm using (iSimple IS77) has a toggle switch for power already. But the danger would be leaving it turned on when connected to a constant 12V.

It seems like running a wire across to one of the fuse boxes might be the best way to go.

[mudman2]

there are spare switched ports in the drivers side fuse box, 27 and 42 seems to ring a bell, use a meter to confirm, I presume this is a true FM Modulator, if so I used one for a few years for iPod and SAT, worked pretty well

[deilenberger]

I added a switched power feed for my backup display/camera by tracking down an empty fuse position in the passenger side fuse box. The power feed is there - what isn't there is a connector to take the power off. Solution to that is to strip back enough wire to wrap around the spade on the fuse, then plug it in so that side goes to the empty hole in the fuse box (and the other side to the side of the fuse position with a connector in it..) It's pretty obvious when you take a look. Be nice to find a source of the female connectors used in the fuse block.. but I was at a dealers when a chap was looking for that part - and the dealer was of no use in helping him. I'm sure Porsche does sell it as a repair part - perhaps a sponsoring parts dealer here might be able to track down the PN..

[j3w]

I don't know if I selected the best solution or not, but it's in, it works and a test drive didn't reveal any faults.

I tested the red wires going to a few of the harnesses in the center console - I have the entire hump removed for another project - and found a switched 12V lead, I spliced it with a piggyback easy splice and grounded the modulator to a ground lug that I noticed on the passenger side of the hump.

There is a foam air duct that goes from the rear seat vent to the center of the dash - I fished the antenna wires up the depressions in the center of that, connected them and put the PCM head unit back in place.

Directly behind the gear shifter there is a metal bridge that the center hump mounts to, the space under it is the exact size of the modulator. I removed the bridge, zip tied the modulator to it, bolted it back in, slid the hump in to check for fit and viola, iPhone plays through my new favorite station, 87.9.

I haven't decided where to place the switch or iPod cable yet - but all signs point to the lower compartment in the console.