I'm bumping this thread because I just fixed 4LO in my 05 Sequoia this way. The vacuum line ran between the actuator and the transfer case then wrapped around the actuator to form a hard 90 degree angle where it connected. The hose literally just fell off when I touched it. The end was split so I trimmed it and I wrapped it around the electrical harness twice instead of around the actuator; this way it connects straight on instead of at an angle.I removed the vacuum hose from the transfer case actuator nipple and it was dry-cracked badly, no way it was sealing. Trimmed 1/2" off the end of the hose to get nice clean rubber, put it back on the actuator nipple, and blammo 4hi was back in service.
I started up, put it in neutral, and hit the 4LO button. I didn't think it worked because it just went into 4HI, so I hit it again and 4LO engaged right away!
Just wanted to share. Thanks.