Instrument light vs radio

As i was changing from the old cdplayer that was in the car when i bought it (rmw -92) to a new one, the instrument backlight went out of work.. The original stereo harness was just cut and the new stereo was connected with some tape and spliced cables.. Now i have three cables that once was connected to the original stereo, that have no function on the new one.. Is the instrument light connected to the original stereo, or is it just a coincident that the lights stopped working when i worked on the stereo?
I must think that anyone else has done this, and maybe can help me?

I'm sure someone will post that knows more than I do about this, but I do know when you put a new style radio in, it affects the dimming feature in your dash lights.

Tom

I figured it out. Half of it, at least. The dimmer dont work, but all the lightpoints are working fine now. I just had to connect the gray, and the green lead in the stereo harness to eachother. I dont really mind having the lights at full effect, but why is the dimmer relied on the stereo unit to work ?