kevinod

Hi Guys,

the PO of my 79 928 (euro) left a bit of a mess or wires around where the stereo used to be (scissors involved I think). I have an ISO harness that I want to put in place so I can hook up a stereo to the car, but I'm having trouble finding out what the various wires on the car are for, so I know what wire in the ISO harness to connect them to, i.e. what colour is the always on power, which is the ignition power, which speaker cable ends up where, etc.

I've searched the forums, google, and the workshop manuals (but seem to be missing the volume with the radio stuff in it... one .pdf has 90 and 97 but not 91 which is the radio section.

Does anyone have that handy or can point me in the right direction?

I've had to replace the electric aerial too, another scissors job.

Kev.

Shark Attack

Do you stiull have the stock fader hooked up? If so, get rid of that and tap in there at the fader. the colors will make more sense to you.

As far as your power and antenna wires. I just used my meter to figgure it out. trial and error taking readings with the ignition sw on and off.

Alan

On a Porsche factory Ground (31) wires are always Brown. The radio has a special switched supply from the ignition switch it is Red with Black stripe and is fed via a series suppressor/inductor (located in the console). On a '79 there was no direct unswitched supply to the radio. You can pick one up from the top of the CE panel - fuse it (and on the radio switched supply) you may well need a supressor on it to eliminate noise.

In general Red wires are battery supplies (30), Red with a stripe is a switched battery supply, Black is ignition switched (15).

The antenna amp lead is a small gauge white wire usually run next to the coaxial antenna feeder. It actually loops through the CE panel with a connection at Pin J7.

Best place to find the speakers is at the fader - extend the wires & loose the fader.

Alan

kevinod

Thanks guys! I'm not sure what the fader is... at it sits right now I have about 10 wires loose not connecting to anything of various colours. Most of them I reckon must be radio wires, so want to connect those to the harness, then work out whatever's left over.

Actually found a pic and put it on photobucket:



You can see the ground wire hanging in the driver's footwell that I must find a home for too, but its the wires coming out where the stereo should be that I'm after at the moment.

Alan

See this thread: https://rennlist.com/forums/showthre...eferrerid=6055

This is the fader (front to rear audio level control) - on an LHD car its next to the handbrake - I'd assume the same on an RHD for ergonomic purposes. It may already be gone - in which case look for a hole in the handbrake cover.

Modern amplifiers have 4 channels so can drive the 4 speaker channels directly - period head units just had a stereo output & required an external front/rear level control. The level control won't handle higher power levels well and after 29 years probably wouldn't even work too well at low power...

BTW the white antenna amp lead is a switched ground that must be provided by the head unit - grounded to turn the antenna amp on.

Alan

kevinod

Ah ok.... in that case I don't have one, only a headlight adjusting control. Don't seem to have a boot release button either. Don't you hate it when you discover there's car toys you don't have? ;]

jleidel

Kevinod, thanks for bringing up this thread. I'm in the same boat, bought the car w/o a radio. I have all the original wires bundled, but no obvious description on where they go. In my case, however, I've decided to replace and rewire all the factory speakers. I'm really only worried about power and power-remote [ignition].

Alan

You may both finds lots of wires that need to be excised - these are wires previously grafted to the car... Porsche wires follow a prescribed color scheme and all the colors are alike (e.g. all the Red colors wll be consistent). Look at thebottom of the CE (fuse) panel to see what stock wiring looks like. You may find a few strays grafted in there too - should be obvious!

Porsche wires are either single color sheath or a base color with a narrow stripe straight down the sheath. Rings, spiral or multiple stripes are not factory.

Factory colors are: Red, Brown, Black, Green, Yellow, Blue, Grey, White

This applies to the body and stripes - but due to color contrast - not all color combinations are used.

You will find wires other than these - figure out what they are connected to... and remove - replace with your new wires if needed so you know the integrity of the connections (no sense having 2 connection on a wire - one you are uncertain of)

Alan

devilinblack

When I tore into my stereo wiring after buying the car I found a couple of old harnesses wired together and a buttload of shoddy connectors.



Here's what I managed to pull out of there that was entirely unused.



If you look at this one, you can see where they tapped in for 12v continuious. Note, it was like that when I removed the panel, no tape or anything covering up their sloppy solder work. Actually I'm just amazed it was soldered as everything else I've found has been butt connectors or something even worse.



Everything for the stereo is now soldered and shrink sleeved. I keep finding remnants of various PO's interesting electrical work though.