Hope you got this solved?
I know I am late to this thread, and I feel your pain (belatedly) regarding the issue you describe. A "bad fuel pump speed control module"? I have been on this forum now for several years, and have never heard of such a thing? No knowledge of a "fuel pump speed control module" and I consider myself to be somewhat good at knowing my car, by now having read almost every repair issue on this site. This one is a 'First'. Do the fuel pumps fail? Yes, eventually. Yet a speed control fuel pump module? Never heard of this one. Not to say that it is incorrect though? My belated recommendation, take it to your Cadillac Dealer and pay to have them scan the system with their Tech II Diagnostics Machine (around $2 to $3 K to buy one). A regular OBD II Scanner is not sophisticated enough.