I have not used 4 wheel drive for some time. While in 2 wheel drive, at 50mph, the diff lock light started flashing, the ABS lights and ESC lights came on. I tried to engage 4 wheel drive while stopped, alternated between forward and reverse but lights would not go out. I think the problem is with the Diff lock sensor. Has anyone else had this problem, and how was it rectified. I have found I can get 4 wheel drive if I switch off select 4 wheel drive, start the engine and reverse, it goes into 4 wheel drive, to get back to 2 wheel drive its the reverse.