Try checking the under-hood fuse box. I think there's a fuse for the radio/acc in there.
Also, as a matter of personal opinion, I would have spliced my RCA's into the subwoofer + and - leads from the Shaker 500 door subs. Then you don't lose any power to the rear speakers and you get a clean signal for your subs. Its cheaper than a line out converter too. 
__________________ Black 2005 Mustang v6, 5 speed, IUP, EUP and Leather.
Razzi 1/4 window scoops, Mustang GT Sway Bars, Flowmaster American Thunder Single Exhaust, Clear Front Turn Signal Lenses, Demolet CAI, X-cal2 91 tune, Hurst Comp/Plus Shifter, FRPP T-Lock, Ford 3.73 gears |