4x4 problems with 06 f350. Different than the other.

[gp300]

I have been reading the other threads on this topic on here. My problem seems different. The 4x4 will always work with the hubs locked in. With the hubs in auto it will work as soon as the switch is turned but then after a few minutes it will quit. The light stays on. If i turn the switch off and back on again it will work again for a few minutes. The defrost doesn't do anything strange and it locks in almost imediatly. Do you think it is still a vaccum problem or is it something else. Any help is appreciated.

[dhanna6powerstroke]

Originally Posted by gp300

I have been reading the other threads on this topic on here. My problem seems different. The 4x4 will always work with the hubs locked in. With the hubs in auto it will work as soon as the switch is turned but then after a few minutes it will quit. The light stays on. If i turn the switch off and back on again it will work again for a few minutes. The defrost doesn't do anything strange and it locks in almost imediatly. Do you think it is still a vaccum problem or is it something else. Any help is appreciated.

I would be leaning toward the electric vacuum pump going bad. Sounds like it works to lock them in but the pump either gets weak or quits completely resulting in the 4x4 disengaging. This is just a guess but worth checking.

[gp300]

Thanks, I will try that. What else does the vaccum pump control. I am guessing the heat/defrost, but that works fine.