91 318i Radio/clock Power Problem

[meh001]

I have a 91 318i. It sat for about 3 months between my son parking it now that he has his 95 318is and my daughter starting to use it because she needed a car. The battery had drained enough that when I went to start it, it wouldn't start so I put the battery charger to it. That worked fine. The battery charged up and the car worked, but my son pointed out that I would need to reenter the radio code to get that working. I did this and it worked fine. turned off the car, etc. When my daughter then took the car (she was driving about 8 miles away) the radio worked and all was well, but when she got back in the car a couple hours later, she called and asked me for the radio code because the radio was showing CODE. I told her where to find it but she couldn't get it to "take." When she got back home, I noticed that not only was the radio code not taking, but the clock module had reset itself. I set the clock and when I turned off and turned on the car again, it was back to 12:00 and wanted the radio CODE. I can't get the radio to accept the code and work and the clock keeps reseting. (And we tried the "turn on the car for 65+ minutes with the radio off" trick, but that didn't do any good.) Any thoughts where to begin looking?

Thanks.

[Kowalski]

i put in an aftermarket radio and now my clock does the same thing your explaining, not sure why tho.... im pretty sure there is an xtra power supply that goes to the clock and is some how wired into the cd player but i rewired it so now its not hooked up but im not too sure. as for you i duno what to say, is there a short somwhere thats causeing it to simulate a dead battery? enough to reset the radio?