i've been looking everywhere for this, i am soooo close to installing my beautiful new head unit. i've been driving around with a gaping whole in the dash for days, and i can't bring myself to pay $70 for such a small operation. would really appreciate any help or links or whatever!

Get yourself a digital multimeter from Dick Smith, Supercheap, Crazy Clarks, etc. You don't need precision here, only basic features. These can be as cheap as $10. If your serious and do a lot of auto elec work, go for a Fluke meter.

Anyhow, with the ignition off, put the black lead of the DMM somewhere clean on the chasis to get an earth connection. Switch the meter to resistance (ohms) and touch the red on another part of the chasis. If you get a reading, then you have an earth. We can continue. If not, try another 2 locations.

Keeping the black lead where it is, start testing the wires in the hole! :dancin:

Switch the meter to DC volatge. Make sure the ignition is off. Look for a wire, maybe yellow or red, that reads 11.8 or more (assuming your battery is ok). This is your "hot" or "always on" which is where the main operting power will come from. Label this wire and put it aside. Make sure the bare wire doesn't touch the chasis!

Next, turn the ignition to accessories. Now look for another wire (maybe red or yellow or blue) that now reads above 11.8. This is your accessories or "switched 12v" or "ignition". Mark this and put it aside, again making sure not to touch the chasis.

Turn the meter back to resistance (ohms). Now you are looking for a reading on a wire above 0 - meaning you have an earth. If you cannot find one, run your own wire (closest distance as possible) from the chasis.

That's your power needs taken care of.

If you have a power antenna, this will be a little trickier - you'll need to expose the wires that run to the antenna so you can test them. Generally 3, hot, earth and accessories. To do this one, once you've found which is hot and earth (using the same process as above) then you need to test between the wires in the dash to the accessories for the antenna. It's resistance, so again anything over 0 is ok.

Finall speakers.

Probably test the ones in the pacel shelf first as they are easiest to gain access to. Put one end of the DMM on one of the speaker terminals, then test for a circuit back in the dash. Anything over 0 is a ok. Mark what side it is, and if it's +ve or -ve. Do this for the back speakers.

The front speaker wire should be the same guage (thickness) and maybe the same colour/brand/style etc. If there are none the same, then you'll have to do the same check on your front speakers. If they are, wait till you have the head unit almost wired. Turn it on and play with the balance and fader and experiment which speaker wires are for what side. Generally the wire with the line of colour down the side is -ve.

Most of all, if you are in doubt, don't try it. You could blow fuses, head unit, etc, in which case it'll cost you more than $70 to have someone fix it. Make friends with the local auto elec rather than a car audio shop and see if they can help you in exchange for something else!

Good luck.