So at the beginning of the summer I had to get rid of my Honda because I cracked the engine block after many hard miles. I waited to get new pioneer 4 ways in my new(to me) 2004 Corolla, for about 2 months.
(kept my old headunit and subs)
I hooked up my door speakers and rear deck speakers over the past 2 days, got the headunit finished today. The wiring in there was much different in the dash than my honda ( the toyota had 2 harnesses and 2 black wires?) , and after hooking the headunit up it just says "Amp Error" and doesn't play any sound. I have my remote wire in but was planning on doing the subs tomorrow.

From what I gathered online, I would guess that it's either from;
*not having my subs in
*having a wrong connection or mixing up the two black cords
*the h/u amp being broken from it sitting around during the time I took it out and decided to put the system back in.

The headunit is a Pioneer DEH-150MP, if anyone is familiar with this model or problem.

What would be the quickest way to trouble shoot what the actual problem is?
http://stereowiringdiagram.info/2004-toyota-corolla/
http://www.fixya.com/support/t15729210-wire_color_pioneer_deh_150mp

^Wiring diagrams for the new headunit and car itself, for reference.