K, so i had to do a sub/amp install on a 2003 ford focus. The guy had basically all the wires you needed and wanted to keep the stock HU. Although ive done many installs, this was the first time I had to go through a firewall. This was actually simple, but I was so worried because I never did it, it took about 1 hour to just find a hole. So I ran the power from battery to the back, not to hard.. pop a couple panels and boom, ur done. So that was all last night... now onto the harder parts..
I wake up calling around to find a Line Output Converter (to convert speaker level outputs to RCA, or low level). I find one and go back to my house. So i use HU keys to take out the HU. Now the tricky part.... I need a turn on remote and attach 2 wires to + and - of a stock speaker channel. I luckly have a digital multimeter so that helped. There was no stock wire diagrams for a 2003 focus online, so i had to test each circuit till I found a 4 ohm circuit. I then burnt off some wire insulant with my torch and soldered the + and - of the LOC to the speaker wires. I then turn on the car and test some of the stock wires for a 12v signal.. I find one, but it is constant, its on even when the car is off.. so i keep trying.. Finally I find a good one, its 0v when car is off and 12v when the key is turned to the first possition and on... I nowrun the RCA's and remore down the opposite side of the car (so you dont have any signal problems).
I hook up the subs, and attach everything to the amp, and presto, were in businesS! It was 2 kicker comps in a bandpass with a kenwood 1000 watt amp. Hit OK, not anything special though.. .
Overalll it was tough, but i learned a lot. You can read all u want, and know all the written meterial, but until you get out there u wont know EVERYTHING.
