Cruise control stopped working on 96 Windstar

My cruise control just stopped working. I have the haynes manual which does not help much. I checked the fuse and the stop lights seem to be working ok. The linkage seems to be ok. I saw the posting about the brake pressure switch and I will replace it but if that does not do it how can I check to see if the module/servo is bad? I need to eliminate that or the button itself. I don't have any codes. I am not sure if a bad speed sensor would show up oin the code reader or not.
Any advice would be appreciated.
Thank You

A bad speed sensor 'should' show up with a code reader.
Mine went bad last month, caused the O/D light on the gear select to blink, did not light the CEL on the dash.

#1 to check is the brake pressure switch on the bottom of the master cylinder, as you mentioned reading about already.
Mine caused my cruise control to not work.
I would hold this as the most likely, and is a inexpensive / easy repair to do yourself.