yellow is power..... red is igntion.. and do you have your antenna plug pluged in.. ive hooked up a fair share of cd players and some for some ODD reason need the antenna pluged in to work

 

hmm, i've never had that ever happen. What decks were you installing? i've done alpine and pioneer without any problems. They've all powered up without the antenna hooked up. i'm not doubting you, just wondering.

 

check the back of the radio, dependig on the make and Model of the radio (Pioneer, Eclipse) there will be a fuse there, that is the inline fuse for the radio. if the lighter is still working take a test light or meter and test the connections at the radio of power.