KaeZoo, you were absolutely right about the +12V Ignition wire. I investigated that thing my friend was told about the illumination wire needing to be +12V -- it's utter bull.
So, thanks for the help I got, but I still know that I wasn't making some simple rookie mistake.
Here's what I found:
-- The Eclipse dash harness wasn't getting +12V Ignition, only +12V Constant.
-- Wiring both the red & yellow wires to +12V Constant allowed the CD player to turn on and read discs, all that good stuff
-- The FACTORY AMP WAS COMPLETLY BYPASSED ALREADY
-- The white/grey/purple/green wires off the internal CD player's amp drove the speakers
-- The DIN adapter with 4 RCA & amp turn on cable did not produce any sound
-- The cigarette lighter is an accessory item, and the +12V Ignition now connects to the cigarette lighter instead of the dash harness
Something about this install makes me think his car had an aftermarket stereo installed before, as the factory amp does absolutely nothing.
BTW, the 4 speakers I installed work really well.
We decided to sell the second head unit to one of my friends. I helped him install it today, and it did work without issues. His car had a working +12V Ignition, but not a working +12V constant. His cigarette lighter was +12V constant, but wanted to keep the lighter plug so we spliced into it and ran a cable through his console. This head unit works fine in his car now.
So, all in all, got to install the same head unit in two different cars with the opposite problems and same solution, not bad //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif