B737NG PSEU light and FMC questions

[sudden Winds]

Hi everyone,

This is a hard one, but I am sure I'll get a good answer here.

Why does the PSEU light illuminate when I press the "ground service" button, when leaving the airplane on ground power?

Also,

How can I change the geometric descent feature to full, in those fmcs that are defaulted to app?

Thank you!

[Yeelep]

With the -5 PSEU, the LGTV (landing gear transfer valve) which is not powered with ground service power can trigger the light. There may be other triggers, but this is the one I'm aware of.