OK, I checked the vac lines, they seem to be in great shape.

I decided to pull the pump, hook it to a vacuum gauge and power up the pump. I ran a hot wire from the battery to pin #4 on the pump, and a grounded wire to #1. The pump runs, but I don't see any vacuum registering on the attached gauge. Is this an indication that my pump is not working, or am I missing some aspect of the function of this pump?

If this is an indication of a problem, would it be something within the pump or one of the 3 smaller vacuum hoses that don't run to the diaphragm connected to the throttle cable?

 

Looks like you have your vacuum test hose connected to a breather port.

 

Sorry @mollusc, the camera angle of that photo is misleading. See below for test configuration.

 

Okay, that looks better.
It's a while since I opened my one up but they're pretty simple inside. They also don't draw much vacuum so maybe it's too low to register on your gauge. If there are any cracks in the lines then you also won't see anything.

 

Thanks @mollusc. I went and pulled another pump at the local wrecking yard today, also pumps when powered as in photo above. I installed this 'new' one and same result. No cruise control.Any ideas/suggestions on what to do now? The dash button works and I pull the "Set" button with no effect.

 

Has your cruise control ever worked?
If yes, have you installed LED brake bulbs recently?

 

Also check to make sure your CC throttle cable is adjusted corrected, and test the vacuum bellows by sucking on the hose that goes to it.

 

The bellow/diaphragm was my problem. Replaced the hoses first then the diaphragm test - ordered a good used one from Ebay.

 

Ahh, excellent suggestions. I will try the suck test on the bellows LOL.
​​​​​​@JUKE179r we have only owned it for 8k miles and it has never worked. Only pulling the button seems to actually move, pushing "set" really does not give much of a satisfying click or move. BUT, I just pulled the tail lights and there ARE LEDs in there. Might that be the issue? Simply swapping them back could be the fix?

 

Yep. You can either replace the LED bulbs with regular brake light bulbs (I think there is 5 of them) or solder in a resistor in parallel to one of the brake lights.
I have LED brake lights and my CC stopped working immediately afterwards. I soldered in a resistor at the left brake light and the CC works.