Stripped Down Electrical Systems for Track Cars

banana944 · 10-08-2009, 07:15 PM

Took my dash out yesterday to remove everything not need for my track car build. I'm looking for some tips from you guys that have done this on what to cut out and how you went about doing this. Any tips, tricks, and ideas would be appreciated.

My goal is to delete eveything uneeded and put eveything I do need on toggle switches. I plan to end up with lights, cooling fans on toggles, and the blower motor on a toggle. I don't care about having a key so I will just do a push start or something of the sorts.

I have a pretty solid idea on how I will wire all the turn signals. One toggle to put them all on solid (night time driving). One toggle for each side of the car for blinkers - 1 toggle for left and 1 for right - each wired to a flasher relay. Keep the standard brake switch for my brake lights. One toggle for the headlight motor and one for high and low beams. This all seems easy in theory but much harder to conduct so give me some kind words.

Cliff notes - Give me tips and tricks to wire eveything needed to toggle switches.

Schumi · 10-08-2009, 08:33 PM

I started on this last year when prepping my track 924S. I pulled everything not needed, and then cut off a lot of the plastic shrink wrap from the factory and pulled out everything that went to the radio and AC system. The AC system contains relays and switches and it's own little electrical loom which I literally just cut out.

Same went with the speaker wires and the wires to the electric/heated mirrors and the door switches. It took a good day's work to get it all traced back tot the main power block and cut out. That's where I ended. For the engine harness, I took it out and re-wired some of it, and re-wrapped it in PET expandable mesh sleeving, looks a lot more professional than the old brown Porsche stuff and more flexible.

Whenever it all gets back together I'm going to try to do an electrical diagramme of it. I think that Eric Kuhns of spec 944 might have a bare-bones wiring diagramme (from the budget spec car thread maybe?) posted if you wanted to start from scratch with the power harness.

As far as the toggles go, it would be helpful to find the factory current flow diagrammes to get the wiring for the turn signals and lights correct- they (supposedly) list the wire color coding which makes it easy to identify which wires do what. Although I have found that sometimes that color coding isn't accurate, but I'm dealing with a 924S instead of a 944, so some things are different between the harnesses.

banana944 · 10-08-2009, 10:02 PM

Thanks or the reply Schumi. Unfortunatly however, I will be rewiring most of the car. The PO did some pretty questionable things and most of the lights are currently linked together via speaker wire...

So, I do not plan on touching the DME harness at all (for now at least). What I plan on keeping is pretty much just the main instrument cluster loom. Everything else I think I will have to do myself. The PO left a trail of destruction, when the dash came out, I found so many wires cut and replaced and wire nuts everywhere and just who knows what he did.

I know I am taking on a pretty big task, and quite honestly, I freaking hate electrical stuff. But I got the winter and pretty much redoing most of the car so I view this as a good learning oppertunity.

banana944 · 10-08-2009, 10:17 PM

My biggest fear is the fuse and relay panels. I have an early 944 fyi. I wanted to do my own fuse panel, and that is easy for all the lights and things. But my fear comes in with the fuel pump relay and the DME relay. I would prefer not to mess those up, I can live with no guages and lights, but the car not running - not so much.. haha

flash968 · 10-09-2009, 06:31 AM

i have found that it is almost always easier to start from scratch on a race car - that way you can build looms on a board and duplicate them in segments later

this also gives you the best chance at eliminating all excess wire weight (and there is a lot) and allows you to eliminate any old or questionable wiring that you may not notice

Aslet · 10-09-2009, 07:02 AM

You can also use modern connectors , so if you have to do work in the future, you are able to unplug system elements! I also plan on rewiring the car and adding a new fuse block, etc... The chance that one of the old wires with break while doing work is go great, its just easier to replace them all.

banana944 · 10-09-2009, 07:06 AM

Yeah after researching on the web, and per my origional plan, I do plan on doing this. I will steer away from the DME harness and build all the lights, fans, wipers ect. myself. I am pretty confident in this on-taking now after some research.

My fear is still just the DME relay. Still have some research on making this all work but keep it coming guys.

ideola · ideola's Garage

It may be more ambitious than what you want to tackle, but I've purchased and will be installing the ISIS Intelligent Multiplex System in my car. Here is a thread over on Rennlist with details, including a complete wiring diagram available as GIF, PDF and Visio files.
X-Post: ISIS Intelligent Multiplex Systems (race car wiring alternative)

banana944 · 10-09-2009, 09:56 AM

Looks like a realy nice system, but at 1000$, it better be!

I figure if I buy good quality wire, some generic switches, and relays, I could keep my cost like 200$.

ideola · ideola's Garage

Yeah, I was comparing to a $700 painless setup. Seemed like a better way to go for my application, but if you're only doing partial mods, it can definitely be done cheaper. In my case, I didn't want to retain a single piece of the 30+ year old wiring.