need pinout for 2003 ford f-series radio

i replaced the factory radio (tape player) with a factory cd player and i would like to install the tape player in my rv. my problem is that i do not know the pinout of the factory radio. i ohmed the lines and found ground and the power line (hooks to protection diode). when i applied 12v nothing would light up. i don't know which pin is the illumination circuit.

if anyone has any information or diagrams it would be a great help.

thanks alot

jason p