So my auto locking hubs have not been working for a couple years and I have just been locking them manually as needed. But now I have a boat and I like putting the truck in 4x4 at the landings just for added safety. It's a PITA to manually put the truck in and out of 4x4 for just a few minutes when I know I have auto hubs. Plus I recently got aftermarket rims and they cover the manual locks, which can be accessed with a screw driver, but again, PITA.

So today I bought the vacuum solenoid valve, whatever its called, and installed it, and they work! But the vacuum pump will not shut off while the 4x4 is engaged. The auto hubs work, my a/c controls work, everything works fine, the only symptom is the pump not shutting off. My a/c stays right where I put it, it doesn't go into defrost or anything, not even for a second, like it used to when my solenoid first started failing. Is the pump running normal? Or is there a leak on the other side of that solenoid? Should I even worry about it if everything else is working?

 

False alarm, figured it out. I had been testing the system with just the key turned on and cycling the 4x4 switch.

I just tried starting the truck and cycling through PRNDL with the 4x4 switch on and the pump shut off... There must be a vacuum release or something at the hubs that wasn't sealing without them being completely locked in? I don't know?