Cruise control not working on 96 Kenworth T600

Hello all! I have a new issue that has developed on my t600. The cruise control has decided to quit controlling the speed, idle control works though. If I hit “set” the truck will just go to an idle...no cruise and the foot throttle seems to be deactivated. If I turn the cruise off it all comes back to life and runs fine. I’m a little puzzled with this. Engine is a Cummins N14 celect. No check engine light and idle control and jakes all work so I don’t think it’s a clutch or brake switch.

 

Thanks for the help! The vss is a 4 wire sensor that splits to two connectors, a guy here suggested I try swapping the two halves to see if signal that was working for the speedometer would allow the cruise to work; the truck wouldn’t crank over as soon as I did that. Still searching...I’ll keep you posted!

 

Update: finally got it working again! Ended up being a broken wire in the harness going to the run. Thank you all for your help!