Radio Code

[Lines Peter]

You can make one for about $3 at radio shack.  Get a cigarette lighter plug,
and a 9V battery plug.  Connect them together...
Before you disconnect the main battery, stick this thing into the cigarette
lighter, then unhook the main battery.  It will provide just enough power to
keep the radio (and ECU) settings.  Couple of warnings:  Make sure you
unhook the main battery promptly after you plug in the 9V battery.  Also
never forget to remove the 9V battery after reconnecting the main battery.
You don't want them both plugged together for long because the 12V main
battery will attempt to "charge" the 9V.  The result is that it will get
hot, leak, burn, let's not go there....
-Peter Lines

Some time ago, I saw a device that preserved the radio coding if you
disconnected the battery.  You inserted it into the tape slot on the radio
and as I recall it had perhaps a 9 volt battery attached to it.