Yes.
Yes. the computer runs the cruise.
The pcm controls the cruise.
The engine computer controls the cruise.
who ever said that a dodge ram diesel does not have a servo it is not true. I have a dodge diesel 2001 and it has a servo and the answer to this question is it had a vacuum leak in the servo vacuum line, changed that and cruise control worked great. the servo is under the drivers side battery.
Trouble code P0594 means: Cruise control system,servo control - circuit open
Check the vacuum lines on the driver side of the engine.
It is the same fuse that feeds the PCM. So if the truck runs and the alternator works it is not a fuse.
LOOK IN FUSE BOX UNDER HOOD
The repair will depend on what part of the cruise control is broken.
77 Speed control power relay circuit It means there is something wrong with the cruise control system. Usually, this code refers to the servo that controls the throttle opening when the cruise is activated.
Far passenger side of the firewall, behind the air cleaner.