2008 first gen f250 super duty 4x4 won’t engage.
It was popping the switch fuse last year but now it
doesn’t. When I switch it to 4 high I can hear something
like sliding switch or valve from under the drivers side
of the truck. 4x4 light comes on also. Mine is vacuum
operated. I have a little pump on top of the fuse box by
Possible transfer case actuator problem. The hubs are vacuum operated but as far as I know the tcase is electric.