4wd low would engage
 

I have a 2005 f150 King Ranch. if I put the truck in 4wd high I have 4x4. If I put it in 4wd low. the indicator light does not go on and there is not a change from 4 high to 4 low. The indicator light does illuminate when starting the truck so it does work. Thanks for any help.

Sorry, have to ask this, but are you doing this while in neutral with your foot on the brake? If not, that is probably why.

I had a problem sort of similer to this in my 06. 4wd would engage in low but not high. What the problem was is that the piece that allows the 4wd to engage in the front end was burred on the end and prevented the two pieces from sliding together. Im not sure too much about the technical aspect of this but i do know it cost around $350 at the local ford dealership to be fixed. hope this helps

from the 4x4's ive driven, you have to put them in neutral, foot on brake, and back up a little ways for 4x4 low to engage, thats how my 2003 is

yeah make sure youre doing it right first, foot holding brake down while in neutral then turn the switch and hold your foot on the brake until the light turns on and you feel the thud. should be a couple seconds.

if that doesn't work then giving the motor a little tap will help if its stuck.

thud, more like SLAM lmao. first time mine did it i was like "wtf was that!??!!?!?"

Did you ever figure out what was wrong with 4 Low in your truck? I have the exact same problem with mine.