that sucks, sounds like it's time to buy a $5 test light.

1. turn the car off. ground the clip end of the light on any of the metal back there. start poking wires. if the light lights up with everything off and the doors shut you've found the hot from the battery, lable it.

2. now turn the key to the acc position, turn all the lights on the car off. start poking again, another wire should cause the light to come on. turn the car off, if the light goes off that's your switched from the ignition, lable that one.

3. repeat step 2 with the headlights on. that will find the illumination wire (if your radio dims with the lights that will control it) lable it.

4. take a 9V battery, start brushing wire leads against the terminals. use a simple process of elimination, don't just grab random wires. the speaker will pop. if you can watch the speaker move note which direction it moves, in or out. if it moves out the polarity you used on the 9v battery is correct. if it pulls back you have reversed polarity, note the polarity and mark the wires. if you mix your polarities your system may sound unusually quiet

5. ground is just run from the headunit to some clean metal behind the dash

Edit: should I put this in the wiki?

Erik P.
Official 2GNT thread Hijacker
Some say that he's driven over more Covenant than he's shot, and that his grenades aren't where you'd expect them to be...
All we know is, He's not The Stig... But he is The Stig's Spartan cousin!