Question about shift on the fly 4x4

[yellowhorse7]

Okay....truck is a 2006 F350 DRW. I jumped in this morning and turned the knob to 4x4 High, per usual. Driving to work on our wonderful snow-packed roads I knew something was wrong since the thing felt like it was only in 2x2 and I was slipping all over. I played with the knob a few times and I can definitely feel the transfer case engaging but it didn't seem like the hubs were locking. So I pull over and turn the hubs from auto to manual and, presto, we now are in 4 wheel drive.
My question is when the shift on the fly knob is turned it should do 2 things....1. engage the transfer case and 2. engage the vacuum actuator to lock the hubs. Is this correct? I figure it must be since I can manually lock the hubs and engage/disengage 4 wheel drive at will. I had a rodent problem and I think it got to the vacuum lines that runs to the hubs. Still need to check. Thanks for any help

[goXtreme]

I had that happen to my 08 work truck and it was a broken plastic splice on the front of the axle on the drivers side. I replaced the plastic slpice with one that I bought from Napa and all is good.

Hope this helps.

[yellowhorse7]

Thanks. I still need to look at it but with 6 more inches coming it can wait!

[goXtreme]

it only takes about 2 minutes to change the splice if that is what it is. On mine, it took a total of 30 seconds to find the problem.

Good luck to you

[yellowhorse7]

Found it and got it fixed. Vacuum hose chewed through by a squirrel!!

[goXtreme]

Kill the squirrel and all is good.

Glad you found it