My Catera WILL NOT START.
When I turn the key to start the car, all of my regular accessories, lights, radio, etc. come on and work just fine, but my starter will not function; the engine will not turn over at all.
It can't be the battery or newly replaced thicker cables; everything else works just fine; my volt meter in the cig lighter plug is always above 12V or more when not on the battery charger and over 13V when on the charger while trying to start. My voltage is currently 12.04V at the positive lead attached to my starter.
All symptoms point to bad starter solenoid or possibly starter...so a couple hours ago I took the starter and solenoid out. I took it to Advance Auto for a starter test. It tested PERFECT so I went straight home and reinstalled it back in the Catera and NOTHING. Same as it acted before. I took it back out; took it straight to Autozone to see if I might get a different test result, but again...PERFECT. It is now back in the car again, and again NOTHING; it won't spin even slightly.
I'm getting suicidal here.

What could possibly be going on with this starter system?!?
On a similar note...what is the other wire that connects to the starter solenoid (the little one connected with a 10mm nut)? Any idea what the voltage should be at that wire when the ignition key is turned all the way to start?
Sorry for the long post.
Any help would be greatly appreciated.
