help.. ecu code 0504 and it says "Automatic Transmission Control Unit Signal to ECU"

i cannot use "search" function, it says i have no access to it..
so, will anyone kindly enough to tell me what is the possibility of faults??

i think we also can find out the transmission codes.. anylinks?? tks..

oh, and my battery has the acid buildup, how do i remove it?? i've tried hot water, and it only clean for a week or so, then the acid will build up again,

tks for all the replies...