Ford 2013 F-650 Owner's Manual page 166

System Indicator Light
Note: If the traction control light does not flash during a traction control
event or stays illuminated, the system is not functioning properly. Take
your vehicle to your dealer for service.
During traction control operation, the traction control light
flashes rapidly and the engine does not rev-up when you press
further on the accelerator. This is normal and is no reason for
concern.
In Off Road or Mud/Snow mode, the traction control light illuminates and
flashes slowly. If a traction event occurs, in either mode, the light flashes
rapidly.
2013 F-650/750 (f67)
Owners Guide gf, 2nd Printing, March 2013
USA (fus)
Traction Control 165