Digital Clock

Hello, I have a small problem. The digital clock in my 1999 Primera (no owner's manual) reads the correct time when the ignition is switched off. When the engine is running another, unrelated, time is displayed with a solid, inverted displayed above the individual minute number. Directly above this symbol is a painted symbol with "2" in it. Can somebody tell me how to display the correct time when the engine is running? Thank you.