420 rancher code 15

getting code 15 on my display and the rancher will not shift. its a rancher at with the es and ps. i have trouble shooted all individual parts of the es system and done tests outlined in the service manual no luck everything checks out. have tried clearing the code but it comes back. at my whits end need a little hand if anyone knows the issue or has the solution it would be greatly apreciated. done the grease fix btw

420 rancher code 15

getting code 15 on my display and the rancher will not shift. its a rancher at with the es and ps. i have trouble shooted all individual parts of the es system and done tests outlined in the service manual no luck everything checks out. have tried clearing the code but it comes back. at my whits end need a little hand if anyone knows the issue or has the solution it would be greatly apreciated. done the grease fix btw