Question about shift on the fly 4x4
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