Audio Systems: little to no fm/am reception, rca cables, bad earth

Question
i installed an aftermarket stereo to a 2000 bmw 328i. i first had problems figurin out out how to power it directly w/ the cars original wires. so i ran direct lines from batt to stereo n from ignition to stereo. i cut the original harness out since it got in the way (taped up the wires so as to not cause a shrt). ran rca cables to amps w/ a remote wire. i bought a simple motorola VW12 euro adapter to connect the antenna. the cd player works fine and so does the aux input, but there is little to no fm/am reception. am i missing a wire? or do i have the wrong antenna adapter?

Answer
Hi Alex.
Sounds like the sort of installation I spent ages putting right. Never hack off the cars connector, always try and use an adaptor harness. If the head unit puts out and the amp and CD works then it's the tuner or antenna that's faulty, easy check is stuff (technical term) a piece of cable about 3 meters long with 5mm bared on the end into the antenna socket on the back of the set and drape it over the hood, you should pick up a few stations, enough to verify the tuner works anyway. That means fault is in the antenna lead, (common) or bad earth on the antenna to body. if you get nothing then the FM tuner in the head unit has been fried.
Peter