How is the cargo door on the 1900D opened? The key combination given in the manual opens the radio stack and the main door while the cargo door remains closed.

SHIFT+E (release both, then quickly) press 2.I assume you tried this?SHIFT+E+2 will probably open the main door and radio stack as you suggest. Remember it's SHIFT+E then 2 on it's own, within a second or 2.This "should" work, but I have seen problems with these type of assignments in FS2004 before.