I've got a 1987 Camaro Iroc-Z which does not start when I remove the factory radio to replace it with a new one. The three cable connectors for rear, front, and power/illumination, at first seem to work fine, as the radio gets powered. The problem is that the black seems to be the problem, as the car only starts if that single connector is connected to the factory stereo. It is not draining the batter, and does not even click when not connected.

 

is the black drawing power or is it a ground