Today I tried putting my '06 XLT into 4wd and nothing happened. I turned the **** to the 4 high position and the indicator light didnt come on and there was no noise from the 4wd trying to engage. 4 low doesnt work either (I tried it in neutral like its supposed to work).

What could be the issue and how do I check it?

The last time I needed to use 4wd was almost 2 months ago and it worked fine.

Ive been having a humming noise coming from somewhere in the driveline (or so I think anyway) for a few weeks now. Im not sure if thats related though. Other than the noise the truck drives fine.

I had an alignment done about a month ago. Would any part of getting that done possibly affect the 4wd?

 

Sounds like your shift on the fly is malfunctioning. Simply take it out, and test the wires to see if they are receiving any power to tell the solenoid to disengage the vacuum. Also check into that humming noise. It could just simply be your tires on the pavement, or it could be an issue with the front driveshaft/axle. Do you feel any strange vibrations or does the vehicle jerk when you are making a turn?

 

I havent noticed any issues while turning.
The tires have been on the truck for 41k miles so its not like theyre new or Im not used to them. They never made any noise until a few weeks ago.
I did have them rotated when I got the alignment though.

Without a wiring diagram Im unsure what to check and with my luck Id short something out.

 

If you don't feel confident then you definitely don't wanna mess with it ha. I can't tell you how many times I have messed stuff up because I wasn't 100% sure and it always sucks adding to the problem. Just take your truck to a mechanic, and they should either find a problem with the 4WD shift on the fly. The problem just sounds electrically to me more than mechanical, but I definitely wouldn't rule out the IWE Solenoid, or a bad transfer case/axle.

 

One of my friends might look at it tomorrow if he has a chance, otherwise Ill probably end up taking it somewhere during the week.

Ive learned to set my limits where Im comfortable with repairs. Electrical work isnt my strong point.

 

Sometimes the electric shift motor on the transfer case sticks. Try tapping on it with something like a screwdriver handle or the like.

 

Where is it located on the transfer case?

Id look for it but its raining hard as hell (hurricane) right now.

 

same exact thing happened to me this past winter wile in mud!! haha no indicator light came on and heard nothing was very weird, and tried messin with and taping on the switch housing, buuuut it ended up just being a blown fuse for the 4wd switch, so check that out for sure! (right foot side of the passenger side floor in front of door)

 

I checked the fuse yesterday and it was good unless theres another one.

The one I saw listed in the owner's manual was fuse #11 and its for the 4wd and ac clutch. The ac is working fine (used it last night and this morning).

 

yea idk which one u checked but there are a few, and the only reason i know that is bc i checked while i was in the mud and it was fine and later found a different one that was blown, so check anything that has to do with 4wd. its a blue one im pretty sure should be a 15. i would look but i dont have my truck right now.