F150 intermittent failure to go into 4wd

[Tom7227]

the 02 F150 with about 160K won't go into 4 wd all the time. It seems to get hung up when it's wet out - or maybe that's just when I need it and try to use it. Any ideas on what it could be? I'm hoping for a broken boot or something on a plug that is shorting out. Not sure it would be worth too much to fix it.

[Tator2k]

Do some searching on F150 forums. The front is controlled by a vacuum valve they like to call a 'turtle' It's common to develop a leak or have this go out.

[Lip_Ripper Guy]

I had this with my 2005. It seemed like the switch wasn't working, but I sold it without figuring it out. Does the dash light come on?

[clayton08]

Ive got an 2002 and had the same problem and it turned out to be the vacuum I paid 600 to get it fixed.

[Scott K]

05 is different. On the 02, the most common part is the lever gets stuck in the front diff. There is a piece of plastic that when you pull the oil filter off, the oil drains on that. Pull that off, the vacuum actuator is behind that. Check to see if it is moving, and if it is getting vacuum when shifting into, or out of 4x4. If it does, and the lever doesnt move, get a pry bar on the lever, and move it back and forth a few times, to see if it will loosen up enough to start working again.