2007 Mitsubishi Eclipse Spyder GT Convertible "603 error code" Questions

What does trouble code PO 603 mean for a 2007 Mitsubishi Eclipse GT? P0603 Internal Control Module Keep Alive Memory (KAM) Error. This code occurs if you've altered your computer from stock settings

...603 PCM KEEP ALIVE MEMORY TEST ERROR. POSSIBLE CAUSE.BATTERY HAS BEEN DISCONNECTED.DUE TO CLEANING CABLES OR REPLACING BATTERY.WHATS HAPPEN WHEN YOU DISCONNECT CAR BATTERY YOUR PCM LOST ITS MEMORY.SO ...