HelloKitty, if you add your e-mail to your profile, it would make it easier to e-mail you any sort of troubleshooting guide if someone has one.
To begin troubleshooting for this problem, you will first need to remove the battery and clean ALL the corrosion out from under the battery, and anywhere near the the cables, replace any power or control wiring that has been sitting in the corrosion and or has any sort of damage to the insulation, cracks or swelling included, it does not NEED to have bare wires showing to require replacement. Next would be to insure that no added optional devices have been wired in (incorrectly).
Check ALL power cables for continuity to the frame. Anything with less than 100k ohms resistance must be fixed first.
With the battery out and not touching the machine other than the battery cables, check to see if this code come on now. If that seems to cured the problem, you will need to get the battery checked by a good battery company. if not, come on back and someone around here can give you further troubleshooting tips.