The installation of a 58V FICM will not cause the truck to throw a check engine light. The BD-Power 1059700-A 58V Fuel Injection Control Module (FICM) can be installed directly onto a stock truck and requires no programing of any kind.
All programmers are only reprogramming the ECM and not the FICM. Programmers are fine to stay installed/ be installed on a truck with an upgraded 58V FICM.
Yes this will be the case when checking voltage through some type of scan tool. You can always test the FICM itself for proper voltage.