99 Jeep 4.0 Cruise wont engauge

I have a 99 Jeep Grand Cherokee with a speed control that does not work. The light comes on when you activate it but it doesnt hold speed. It has vacuum to servo. It has a new brake switch. There are no codes in the pcm. The voltage changes when all the buttons are pushed. Here is the odd thing. The "set" speed is no where close to actual speed on the scanner. Is there another VSS for the cruise except the one for the speedo?

Turns out the nipple is broken off the speed control servo. No vacuum to the servo. Ordered new one, will know tomorrow if this fixes it.

I have the exact same problem, the dash light shows that the cruise control is working but it will not engage. Could you tell me a little more about what the speed control servo nipple thing and where I can find it? you can email me direct at Steve_keefer@msn.com thanks!

Under the battery , You have to take out the battery and tray. There is a vacuum resevour and servo with rubber hoses.