Ok forgive me but i posted this in 2 places to get a better repsonse.
Ok, I have an 83 GSL

pulled the stock head unit, speakers and amps. Re-ran speaker wiring through stock locations, and pluged it all into the harness that came with the new head unit using quick connects since they did not have a mazda harness. Anyways, the problem is that I can't get the damn thing to turn on, I put connectors on the red and yellow wires (accessory and battey, respectively) and then ran the ground wire to a bolt going to the floor on the center console. I plugged the red and yellow wires into the original harness (car side) according to what the wiring diagram showed as being the battery, and the accessory, and then left the remote antenna wire disconnected (have a solid antenna). After I had it all plugged in I turned the car on, and voila-NOTHING. I plugged the old head unit in to the wiring harness again and it failed to turn on. Could this be bad wiring or a blown fuse? The old head unit workd but fails to work now, does anyone have any ideas? Thanks in advance

 

Ok, what I did when I installed my stereo is BEFORE I put anything in I touched a wire to my battery then grounded another one and then sliped those into there correct places on the back of the deck to make sure it turned on correctly. Basically, I'm saying to make sure everything works before you install anything. Then if it doesn't work you can check your wiring without undoing anything.

 

Do you own a Voltmeter? or multi meter? or a 12V test light? You should try them! they work well

 

Go here and see if it helps.
http://www.installdr.com/Harnesses/Mazda-Wiring.pdf

 

If He re-ran his wiring then the stock wiring diagram should be useless. Sorry, if i'm sounding like this isn't a great resource. I'm probably bitter because they don't have anything like that for a sa (78-80).

 

could be both, bad wiring caused blown fuse.

 

ok, checked the wiring to the diagram AGAIN last night, and it did nothing...all my fuses are good so the wiring is all thats left, but what made it go bad in less than a month? my g/f brother unplugged the old head unit (stock) which would turn on but did not work...if he didnt disconnect the battery when he pulled it, could that have caused the wiring to roast itself? If so, whats the fix?

 

Always run new power wires. Did you check to see if those lines you are using has power?