Wiring Loom Question

[944Fripp]

First of all happy new year to you all, I hope you've all had a good Christmas and enjoyed your new year celebrations.

I was lucky enough to get my hands on a very dinky but pretty powerful active sub over the Christmas period and was thinking it would balance out the rather weedy sound (base is just not audiable on the motorway!) from my current system. It even fits perfectly in the space on the opposite side of the battery in the boot.

So, I've hooked up the amp to the battery, earthed it and fed the RCA cables through to the head unit which has outputs. I now need to wire up the remote switch on cable which as far as I can tell tells the amp when to switch on and off and requires a constant 12V feed when on. Obviously I don't want this constantly on as it would drain the battery and need it to switch on when the head unit is switched on and off respectively. I have thought of splicing the connector into one of the speaker cables (which would work assuming I never use the fader!), however I was wondering if anyone knows of a better one to go for? Some say the blue one but that's the power from the battery and I think that would keep the system on constantly right?! Others say the antenna but that would mean the sub would only work when the radio is on...not ideal!

I'd love to know what all the colours mean and where they go! It's all a little bit complicated for me I'm afraid!

Thanks to all.

 

[bmnelsc]

I found this on the web a while back. Forget the original source but if you search on this you should find it.
924/944/968 Stereo FAQ
You will find there is a constant 12v in addition to the antenna but you will want your amp switched some way.

Also - Porsche workshop manual has a good description of the wiring. I found my S2 had the wiring for the phone system, the 10 speaker audio option AND the standard 6 point plug for Blaupunkt stereos already in place. And someone had added a sony stereo so I had that plug there also.

Hope this helps

 

[peanut]

this might be useful.
http://www.installdr.com/TechDocs.asp

 

[944Fripp]

Thanks for those answers, good info Nick. It's a little clearer and also, pretty obvious that hooking it up to the speaker isn't going to work!!

I've been poking around with a multimeter to see if I can find a wire that shows 0V when the ignition is off and shows aprox 12V when the ignition is on. I found quite a number of wires back there and some seem promising however there's one thing I don't understand: the multimeter displays 12V alright on some of them with the ignition on but shows aprox 3-6V when off. What's going on there? Shouldn't it all be off or is it something to do with the stereo's memory?! Maybe I didn't ground the multimeter properly, would this have that effect?

Maybe this isn't for me..I'm a nuts and bolts type fellow and don't really understand electronics! Perhapse a trip to someone who really knows what they're doing!

 

[zcacogp]

Your stereo will almost certainly have an output which goes to +12v when it is turned on. This applies to the stereo as a whole - so will go to +12v when it is on radio, CD, aux input, whatever, and will be the connection used to turn the aerial amplifier on as well (the aerial amplifier will be working even when the stereo is playing a CD.)

This is the connection to use. And you will need to run a seperate piece of (thin) wire to the back of the car to connect it to the active sub. If yuo already have the RCA cables in place then take it along the same run (and think about doing it all at the same time with your next car! [] )


Oli.