You need to check your radio harness for a constant power supply. That is why it only works the way you have it now and it has no memory, it's getting it's power from the key and nothing else.

With the dome lights only working when you turn the key on, I'm wondering if you didn't try splicing into the wrong wire for power. Was it like that before you started messing with the wires?

It's possible that it's just a blown fuse, but when dealing with a harness that someone else hacked apart it's anybody's guess.

 

Just a thought, when you tie together switched and constant power, you're bypassing the switched 12V power relay. It's possible that either the switched power circuit or the switching relay is damaged although I cant't understand why...but hey...stranger things!?! I'm also guessing the ECM might just be confused by the change in system load...guessing of course.

 

 

There is definitely more wiring issues at work here. Make sure all of the fuses are there and working in the fuse panel on the side of the dash and under the hood.
Fixing someones hacked wiring job is one of the hardest things to do on a vehicle. Don't let it get you down, and take your time when you trace things. It's very easy to over look a broken wire that doesn't show through the insulation.

 

 

Check the IOD fuse in the fuse block on the side of the dash as well. It's under a little cover, and doesn't look obviously like it is a fuse.

 

 

 

What was the issue?