E450 cruise control quit.....need suggestions.

Start by getting the pressure switch on the master cylinder replaced. There is also jumper harness with a fuse built in that should be installed (this part is FREE because it is part of the recall).

If it is not a fuse and not the master cylinder switch, it is likely the control module or the motor. The modules are expensive, but you can usually find one in a junk yard for less than $50.