new radio instalation issue.

[amigo26]

Just attempted new Pioneer radio installation on my 1991 NA auto. Followed all the connection instructions connected the radio via the 2 plug adapter to the 2 white plugs in the radio cavity. Connected the battery and wow and behold the radio lit up like a christmas tree. Problem was I couldn't turn it off. So I disconnected the constant feed (battery power) and that did the trick. Wrong!! Radio went off but then turning on the ignition did not turn the radio on??? so I swopped the ignition and battery leads around, same result radio wouldn't turn off.. I checked the large white radio plug under the dash and found the constant power lead had power, no surprise there, then checked the accessory power lead and ??? constant power?? the ignition was turned off. So, what's happening can anyone advise me.. I've done nothing to the 2 white plugs under the dash just connected them to the radio with the above result.???