Have not worked on this truck in a while but l think that there should be a code in the bdi screen also if you pull the cover on the top the plastic cover and open the doors the traction controller Curtis and fuses are there check them and see if the small light on the box is lit it could code there also l believe you can look at most things if you turn the key on and hit the horn button two times very quickly then use the forward and reverse handle to look at the throttle and other inputs if you get the code get back to me l will try to help you the traction controller is black and l believe the steering controller is silver.hope l was some help.