Also having 4wd disengage issues:(
I've got a 1998 F150 4x4 5.4L Shortbed with about 130,000 miles. Its got the Shift-on-the-fly and automatic hubs.
Recently got some snow and thus discovered an issue. I can shift into 4H the indicator comes on in the cab and when I turn sharply I feel it jumping, it also seems to shift into 4L as that turning issue goes away. However when I shift into 2H from 4H or 4L the light goes off yet its still difficult to turn and such (I can hear what sounds like the front drive axle going). If I stop and back up maybe shift into park or neurtal it will finally shift out of 4H and then back into 2 H.
I got under the truck and the shift arm on the actuator moves, so I think that is free. I looked at the vaccum cables and they look okay from a glance. Is the diaphram on the actuator a 2-stage or 1-stage, as I am wondering if its bad?
Could one of the selonoids/vaccum switches be bad? I tried to order one from the local NAPA and they can't find one, they think its a dealer part only.
I was thinking about buying new vaccum lines, yet the same NAPA dealer did not have lines specific to my truck.
I'm new at the 4x4 repair, so any help would be appreciated! Also, any diagrams on the 4x4 or vaccum lines would be also great.