The wiring harness adapter is a good idea to try, but there is a chance it will not work with your cars wiring. I've tried that 4 times in Volvos, it worked once.
If you are just replacing the head unit and the harness adapter does not work (adding amplifiers is a lot more advanced):
- Look for pairs of wires that are the same color, they are the speaker wires. There are 2 per speaker, the main color of the wire will be the same, one of the pair will have a different color stripe.
-Now you only need three more wires, constant power to the fusebox/battery, a wire that powers up with the ignition, and a ground wire. This is where you need a meter or test light (which is easier and cheaper than a meter)
If using a test light, hook the alligator clip to the cars chassis, like a door hinge or other large chunk of steel. Ignition key off. Touch the lights probe to the remaining wires, the one that makes the light go on is constant power. To find the switched wire, turn ignition key on, repeat above test and a wire that didn't previously light up now should. The ground should be brown or black, and try to follow it to where it is screwed to the car chassis, or run a new wire to the chassis.
-Hook up power and ground wires, ignition on, get music playing, start touching the cars speaker wires to the stereos speaker wires. This will tell you which set of speaker wires in the car is for which speakers. Match them all up, done.
Note - please do not use wire nuts in the car, or rely on electrical tape to hold them together. If the power wires separate, there will be blown fuse at best. Get a set of wire strippers and a crimper (or a combo tool with both) and use insulated butt splices or male/female spade terminals.
You can PM me if you need more info.
