Stereo Wiring

[robyculver]

I'm not that familiar with car electronics, but I'm wiring in a stereo to the car I'm driving and there was no factory wiring harness. I have grounded it to the chassis and wired in all my speakers. Is all I need from there a constant 12 volt run from the battery? If not what else do I need and should I put say a 10 amp fuse on that run from the battery?

[metallikat]

ive done several stereos without any harness. i just hooked up the wires. here are your basic needs...

constant voltage (often yellow)
ignition (often red)
ground
speakers

these are usually identified on the stereo unit. ive had luck with just taking a wire straight from the battery to the yellow wire, which is also called the battery backup lead, it really just saves your presets i think. im not sure if its required for functionality or not. the ignition wire; basically what i do, is i get my multimeter out, set it to 20 on DC, and start looking for wires that register 12 volts (give or take) when i switch the key to the on position. ground wire is very important, so after that..you should be good.