Andres;
You need to perform interactive dianostics of the truck's control to define the power assist steering issue. The way to do this is to push FN 1 and FN 4 in while you simultaneously turn on the key switch. You will see the self check menu in the display screen. The power contactors in the power distribution panel will all close and open in an orderly sequence. Push the FN 3 Diagnostic check window 500 should now appear. Now push FN 1 Error Memory window 510 will appear. Malfunctions which have occurred in the traction, loading, and power steering systems are recorded.