Its a code for low vacuum conditions. Inspect your vacuum lines for a leak. Including to the front hubs

 

Might be a stupid question. I park my truck on a slanted driveway and each morning when I start the truck I get a display on my screen saying to check brake system and the light will stay on until I turn the truck off, once I turn it back on after driving it I don't have that screen displayed. My question is, would being on a hill have anything to do with it while starting like maybe showing a false low in a reservoir? My braking feels normal and no different than it ever has.

 

Yes most likely your brakes are down around 50% and when you're parked on the angle it's enough for the fluid level to trigger the switch. Inspect your brake pads.