PVH Solenoid - no auto hub lock / unlock

[cmayer]

So, my ESOF is doing the typical switch to 4x4, hubs do not engage, and AC diverts to safety mode through the defrost system.

Transfer case shifts and all dash lights are functional. Vacuum pump works and appears to operate correctly.

Tested the HVAC vacuum lines and did not find a leak. Also the HVAC system works perfectly up until I switch to 4x4. Check all connections behind the glove box and everything appears correct.

Tested each hub individually and they locked up with 12-14 Hg and held vacuum.

Tested the ESOF vacuum lines from the PVH Solenoid and they held 14 Hg and locked the hubs.

After these steps, the only thing I can think of is the PVH Solenoid. I see there's a way to test the PVH for vacuum leaks by applying 20 Hg to the circuit, but I'm not sure where to apply the vacuum.

Is there anything else it could be at this point other than the PVH Solenoid?

Thanks!

[NYC F-350]

Check out the pdf file I have attached. It has all the pinpoint tests for the whole system. Everything you ever wanted to know about the ESOF system, and more.

[cmayer]

Thanks! Printed it and will diag. this weekend.

[robsranger]

Just found. Thanks for the PDF NYC, Helped me!