have an 05 2500 cummims and when i get on the highway the transmission wont stay locked in 4th and drops to 3rd and goes back and fourth. The codes it was showing was for the low output speed sensor and transmission control system electrical. I replaced the sensor and it didn't make a difference. I also changed fluid and filter and it didnt help. Anyone familiar with this problem or have any ideas please help i really need my truck for work thanks

 

The 2 wires where frayed near the bell housing fixed the wires and its works fine now