no illumination lead on head unit

i just installed an audiophase CA711 cd player in my 1993 Geo Tracker. The vehicles wire harness had already been cut off when i bought the car last week, so i wired the the unit in without it. but i am confused because there is no illumination lead on the back of the radio. i thought perhaps the LCD Backlight would draw its power from the switched 12v+ connection so i didnt think much of it. but tonight i noticed that the backlight doesnt work at all. I've triple checked all the wiring using this chart  ( 1992-94 Geo Tracker Stereo Information ) and the chart on the top of my head unit, and everything matches up. the buttons light up and i can see the display during the day...just no backlight.

Then your backlight is probably dead. The illumination lead does nothing more than dim the display when the headlights are on.