Under Dash Wiring Job

[crashr]

This winter one of my jobs to do on my 75 911 is to clean up the rats nest of wires that are hanging under my dash, mostly on the drivers side. My plan is to go wire by wire and figure out what I need and what does what. I have several cut wires and several wires from what appear to be two old alarm systems as well as a few radio installs.

On ebay I see the Propero Porsche Wiring diagrams for a bunch of different years of 911's. My question is has anyone ever used these before. For 25 bucks it looks like it might make this job a fair bit easier for me. Just want to know if anyone out there has ever bought one of these and were they satisfied with the product, also was it accurate?

[LM3929]

Even though you are from TO let me check tomorrow to make sure that I have one for your 75 and for the cost of the copying and postage $5.00 Canadian I can copy the ones from my manual for you.

[Ole Petter]

Hi, I recently did this. An old alarm system is really a challenge to remove... My car had cables and connections just absolutely everywhere. The drivers door looked like a "rats nest" and the most absurd thing was what looked like "old style school bells" was used as alarm-horns! There was one bell in the engine compartment and one more under the car next to the gearbox! I am still shocked by the weight of the things.
The bad thing about the alarm-system though was that the cables used was "too thin" and seemed to make the one of the fuses go warm. Of course the cable going from the fuse was hot as well...
It was a really great feeling to have cleaned all of the alarm-system out. I also have removed all of the stereo/speaker/antenna/antenna-cable from my car. That was really easy, as it was just a case of following the wirering from the stereo system and remove everything.
The bonus of all this is a much cleaner-looking electrical system, especially in the trunk and under the dashboard. Also nice to get rid of some problem-sources.

I would like to go a step further and remove the switch and everything to do with the heated rear window. Also the interval wiper cabeling and switch, as I have no use for either ot these things. But of course this would be much work! I am somewhat conserned as to if this would give problems with "the current" electrical system. But I will try and think something out. I will consult an electrician for advice on this...

Good luck with your project!

[Ole Petter]

By the way, I have a Haynes 911 book. It has a complete electrial diagram and is a great help.

[RoninLB]

Originally Posted by Ole Petter

I would like to go a step further and remove the switch and everything to do with the heated rear window.

I removed "heated rear window" relay and plug + wiring on engine compartment electric panel to make room for an ignition coil. The dash board switch and wiring isn't an issue.

[RoninLB]

MSD coil

[crashr]

Hi Guys,

I have a Haynes book which I have been using up till now for all my electrical issues, I also used it to do the wiring for my 3.2 conversion. I just find it is hard to read and follow at times. I thought that this large laminated and color coded wiring diagram was a good idea and something I could bring with me and see in the garage. The haines manual you need to stare intensely at the labels to try and make them out. This aftermarket wiring diagram is labelled and color coced as per the car.

I might give it a go just to try it out. This Prospero and ebay has several thousand buyers all that have given good feedback. I will let you guys know what I think of it.

[moneymanager]

I got the charts a few months ago and have used them several times. As best I can tell, they are accurate. They are certainly much much easier to use than anything the factory ever did.

[Ole Petter]

Ronin, thanks!
But which ones are the relay and plug for the rear heated window?

It was great to see how you had mounted the MSD instead of the unneccessary relay!