new owner, car audit & inspection : custom wiring

Greetings, new 996 mk1 owner (1998, 156000km, very good condition) & porsche newbie. I'm preparing for a certain number of (small) mods like gate opener, GPS tracker, footwell lights and 2 din car radio (A/C controls moved etc). As I'm inspecting the car central / bottom console, fuse box etc, I noticed a few additional wires (I'm the 3rd owner) under the hash tray, behind the drop box (LED) and there's this 5 wire harness that was hidden in the velcro carpet, it seems to continue to the passenger side but I don't know where. the wire tap near the fuse box seems to te be related to the horn, it travels to the trunk and it also runs with power wires to the central console. I have that additional anti vandal stainless momentary switch near the ash tray (it's not connected to anything anymore). The LED routes along the hand brake and jumps deep in the car, maybe going to a control unit (?) I'm obviously not after a magic answer like "oh that was made for *this* particular reason" but maybe some pointers : - the car had a gps tracker which got removed (do they get connected to the horn ?) - additional alarm ? - car lock switch system (switching off the fuel pump for instance) ? - use of the LED and stainless switch ? - hand free phone kit ? (the car has a basic tape becker + 6CD changer, no PCM) I thought I'd ask the experts :-) thanks

I think you're on the right track. All the things you mention are common retrofits - also radar/laser detectors. The only recommendation I'd make is to be sure to cover/insulate those bare connections when you're done! Good luck

thanks a lot. I've just ordered some fabric tape to make a more professional looking wrapping of those and avoid too much PVC electrical tape. I'll probably check if those are use somewhere and maybe remove as much as I can. In the meanwhile, I'll prepare for the 2 din GPS / radio and route all my new wires for the footwell lights (I'll make them with trunk light clear inserts in the carpet trims, and some leds as I'm replacing all interior lights with warm white leds) I have an extra question for an additional anti start / anti thief hidden switch: I've see a lot of people using a switch on the power side of the fuel pump (like, wired in series with the pump fuse for instance). I understand that it's easier to do that as (probably) the access to the fuse is easier than the relay, however (Electronic engineer here) I'm concerned about switching the power load and having the contacts corroding over time (relays have special coating on contact blades). I was thinking about rather switching the coil of the relay, which is definitely lower power and safer in my opinion. Thoughts ?

I'd solder and heat shrink those wires.

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Which ones ? Some of those are not going anywhere or and not attached to anything so I understand the heat shrink but I don't see the point of soldering them ?

^^ anytime you have a twisted bare wire connection like shown in the photo, you run the risk of oxidation/corrosion, so the solder would be insurance against that... Then heat shrink wrap and you've got a truly permanent connection. As for the fuel pump shutoff - I'd think a simple inline switch would be very effective...

Good points regarding oxydation: pre-tinning then, not soldering per say. Regardless, unless those are made of oxygen-free copper, corrosion will always creep up even it the tip is tinned : what we do in electronics is heat-shrink the tip of the wire with a few mm extra above, then pinch that extra heatshrinking tube to seal it. A dab of hot glue on top of the tip of the wire prior putting the heatshrink makes it even more water / moisture proof I didn't realize you talked about those twisted wires, I indeed fixed that after taking the picture with a Wago(R) block. They have isolated and solved most of my temporary or permanent wiring. I usually add a drop of 3-in-1 oil in there (which has good electrical property + oxydation preventing) before snapping down the wire in the Wago.

So, i tracked down all the weird wires and re did the radio harness. one set of wire is indeed going to the horn and i tracked 3 wires going to the trunk and end in the front fender / spoiler connected to this. I have no idea what that thing is, any idea? It could look like a Pitot probe or a temperature sensor. Or a mini alarm siren?

That’s the ambient air temp sensor

Thank you very much I assumed in that the wires are found are going somewhere else as I can see the temperature changing on the on board computer as it's been activated despite I don't have the stalk