This is my second post (the first being about the fuel sender).
I have a '95 Pathfinder bought at an auto auction. The cruise control (ASCD)
worked fine when I bought it. Then it stopped working.

I cannot remember if it quit before or after I had a front end collision when a Mustang pulled out in front of me from a parking lot.
In any case, I just replaced the vacuum hose to the ASCD actuator under the hood, passenger side, and the button in the brake pedal that operates the cancel switch next to the stop light switch.

These two things did not restore operation. I have the wiring diagram and can trace and test wires and connectors. However it would be hard for me to know what goes on, or into and out of the ASCD control unit or some of the other components.

I have checked both fuses that seem critical according to the wiring diagram.
Maybe this is a thing that requires the dealer's computer to diagnose?

Is there a first step, go-to-thing to check that is notorious for causing trouble?

Thanks you for your help,
Richard
1995 Pathfinder 2WD

I noticed that a lot of you have viewed this post but no-one has replied.

First, my Pathfinder is a WD21 series. It has a 94 build date and a 95 owners manual
Simply... how do I diagnose the cruise control ?
After it quit working I replaced the vacuum hose under the hood on the pump mechanism and I replaced the plastic button on the brake pedal that disconnects it when you press on the brake.

But it didn't start to work again. What should I test next?

Thank you,
Richard
94-95 Pathfinder 2WD

There is no dealer "computer" or scan tool to check anything on a WD21 except for the Kent Moore "checker box," which is used to pull ECM codes without having to remove the passenger seat, and the security system diagnostic tool. Otherwise, everything else is tested by using a 12v test light, a multimeter, a Nissan service manual and experience.
I highly suggest you get a Nissan factory service manual for your vehicle. You can sometimes find them on Ebay for around $35. You might even be able to find a downloadable version at NissanHelp.com or Nico Club's forums, but I'm not sure because these manuals came out before Nissan started releasing their service manuals on CD (personally, I prefer the paper manuals). Another option would be to get a vehicle specific subscription from ALLDATA which will give you the same info. The service manual gives step by step directions to test most systems, including the cruise control, along with wiring diagrams, connector views and locations and a wealth of other information.
One issue that sometimes pops up on mid 90's Nissans that could affect the cruise control involves the speedometer head in the cluster. There are 4 screws at the back of the cluster that secure the speedo head to the cluster as well as make the electrical bridge between the head and the printed circuit. The threads in the speedo head can develop small cracks and cause the screws to become loose and create a poor connection. Removing the cluster and tightening the screws can fix the problem temporarily but the long-term fix is to replace the speedometer head unit. I can't say this is your problem, but something to keep in the back of your head!