Not sure where to put this, but this looked like as good a place as any, mods move as you like.

Anyway, my baterry is now 7 yrs old and needed to be changed, so got the battery and changed it (have got to say it was the easiest battery I have ever changed, cleanest also). After changing the battery, naturally I need to see if it will start and I'm also expecting to have to reset all my radio presets, but when I turn my key on, all my presets are still there, they didn't all clear like I have seen with other batteries I have changed before. The only reset I had to perform was the "tire pressure" alarm setting.

Now I have my theories; small capacitor that holds a slight charge for a short period of time or there is a ROM chip in the unit that has memory. I might add that the radio/cd player is OEM, came with the car.

Any thoughts.

cajun

That theory is as good as any. I've replaced a battery, and had it disconnected for various reasons, and it held the station memories. The time, however had to be set. I hadn't delved into the reason.

There is some residual power that lingers.. you moved fast enough and got lucky.

I had my stock HU out for 20 minutes the other day and i to went WTF when everything was the same.

I was not so lucky. I had let my battery partially run down once while working on my 2000. It was in an accident, sat for a couple weeks, and I opened doors & trunk a lot.

When I tried to start it again, I didn’t realize battery was drained that much. I turned the key and it did the typical repetitive starter solenoid clicking with courtesy lights dimming. The radio was on when I did this.

After re-charging battery, all pre-sets were cleared. Now the pre-sets don’t work properly. You can program them all OK but after awhile, some of them will loose the setting and start seeking once you hit the button.
I think display says “AF SEARCH” while it is seeking.

I’m guessing there must have been a voltage spike.