Dimming the lower EICAS/ECAM

Does anyone know how to dim the lower EICAS/ECAM? For the 747 the lower display is blanked out to avoid distraction except when needed. I've developed the logic to display the relevant synoptic display when appropriate but I haven't figured out how to dim the display when not used.

For the 747, when you press the STAT key twice, it is supposed to blank out the lower EICAS/ECAM. I've tried several alternatives, including zeroing out offset 55F3. It doesn't work. Also, trying to toggle offset 0510, bit 4, pmSD2Inop, doesn't work -- it blanks out everything, not just the lower EICAS/ECAM.

Any suggestions?

Cheers,

Jon