i'm doing a head unit install on my '03 sedan EX.. i got everything torn down crimped the wires plugged it in and my new alpine receiver sounded great... then i disconnected it so i could reinstall the dash and AC controls and i plugged it back in and it wont work at all.. also, my factory unit won't even give me a 'CODE' reading when i plug it in now... i probably should have just taken it to a professional, huh?

Check the constant power source for voltage, and of course all the fuses.

how would i go about doing that?

Is the car on? First step. Second step, check the fuses in the fuse box. If thats not working, check the fuse on the back of the receiver. If you got an amp check the fuse on that also. Its most likely a fuse problem.

omfg u should not be allowed anywhere near an electrical system. put a meter on it, or a test light. Recheck all ur connections and fuses

lol^^^ hey man be nice... Just check the fuses make sure u didnt blow anything. The fuse box is under the steering wheel to the right. look in the manual to see what each of the fuses goes to. DISCONNECT the negative battery terminal before working on electrical for ur car. Simple task, may have to redo ur presets but who cares, better than blowin somethin up!

Oh, check the wire connections you made also, you know where you crimped the wires and such.