4high light stays on and never flashes when you try changing to 2WD or 4low?
Flashing 4WD light when moving the dash switch usually means shift motor issue
Check fuse #27 in ENGINE fuse box
Check fuses 10 and 28 in CAB fuse box
Is the Ranger IN 4WD, or is the dash light incorrect?
If you are in 4WD when you turn you can "feel" the front wheels pulling you, "feels" much different in 2WD
2010 4x4 system has 3 parts
Switch on the dash, never breaks, just 3 resistors in a box
4x4CM(control module), its behind the radio in the dash, in 2004 and up, known issue, but usually no 4WD lights at all when it fails
4x4CM is what makes the "click" noise when changing from 2WD or 4WD and back, it has 2 relays inside
Shift Motor, fails from disuse more than over use, but its the ONLY moving part in the system
You can tap it with a hammer, the "motor" part, and see if it starts working again, the brushes get stuck from disuse
It can be pulled off and tested using vehicles battery or other 12v power