Electrical Gremlins: Engine runs without key and Gauge Cluster Power Problems

Before I start, my car is a manual 1999 Carrera. So I've got some odd electrical issues, some may be related and some unrelated, but not sure where to start with diagnosing. I've done some attempts to diagnose but not gotten vary far. I did notice a few wires under the dash spliced near the ignition switch, but I can't find the right wiring diagram to figure out what it is. I have a feeling the previous owner did something to bypass the immobilizer or something along those lines, but I'm not sure exactly. I don't know if it's related, but the only key I got with my car was a VW key instead of a Porsche key. All of these happen with a full battery, recharged on trickle charger . 1. When the car is powered off with no key inserted, the cluster screens flash on and off, as though cluster is gaining and losing power. 2. When you do a cold start in colder temperatures (outside temp, not engine temp), the gauge cluster acts up. If it's below maybe 50-60f outside and you start the car, the cluster acts like it has no power, no needles or light to anything including screens, but the warning light row at the bottom still work. Additionally, the oil light and brake wear lights under the cluster are illuminated. Once the car has warmed up partially, the lights for the gauges turn on, but the needles stay stationary. At the exact moment the gauge lighting and screen back lighting turns on, the brake wear and oil lights both turn off. Once the car is warmed up further, everything turns on and acts normal. No warning lights, or anything and it acts 100% normal. 3. This is the weird one and it doesn't happen 100% of the time.If I get home after a drive at night where I've had the headlights turned on, if I turn the ignition to the "off" position and remove the key without turning the headlight switch to the "off" position, the engine will continue to run. The radio and accessory electrical parts will turn off, but the engine keeps running until you switch the headlight **** back to the off position.

You need a new headlight switch and a new ignition switch. You may also need a new ignition lock if the car won't completely power down with the key removed - after installing the new ignition switch.

I'd change out ignition switch first, (just electrical part), that could fix all the problems. But...from how you explain it, could have a couple thing wrong here. . might also have a faulty light switch. Take your choice what to do first, light switch is the easiest to change out.. Both are cheap easy to change out (kind of), and very common problem areas on our 996. looks like theprf beat me to it... lol

Did you just buy this car with these issues ? OR did this issue occur after some repair/work ? OF did it just pop up out of the blue ?? Sounds like crossed circuits... If it just happened out of the blue I agree with the perf and allcool that likely the heahlight switch or ignition switch, both have a lot of internal circuits that can cross/short together...

Seems the previous owner had hacked the transponder to complete the circuit to the signal transformer. I�m fairly sure that your Volkswagen key doesn�t have the RFID pill needed to activate the transponder. Also your ignition lock isn�t disconnecting terminal 86S when key is removed, ignition lock might not be a Porsche part or the ignition lock is worn.