06 w900 speedometer jumping all over

613054

{"text":"My speedometer will be working fine, then randomly just jumps up or down. It will even happen when the truck is idling. It will kick the cruise off when it happens, and when it happens under load I can feel the motor kind of lug. I have replaced the speedo sensor with no luck. Truck is 06 w900 with a CAT engine and 18 speed eaton trans. Any ideas??","pics":"[]","canComment":true}