Hi again.

I am having a problem with my on-demand 4x4 not engaging when I rotate the switch. The light comes on 4x4 and 4x4 Low but it isn't actually engaging. I have to manually lock the hubs to get it into 4x4. I still have a/c and heat and defrost. But that did fail once for about a week. I pulled the Pulse Vacuum Hublock Solenoid - F81A-9H465-BA but have no idea what the 3 contacts should read on a multimeter. With the engine running, one of the vacuum lines has a weak vacuum and nothing on the other one. Does anyone know what the problem could be?

Thanks

 

https://www.dieselbombers.com/ford-p...uum-leaks.html

I have the same problem. I purchased a long piece of hose and tried to diagnose if I had a vac leak. I found that my drivers front hub would not hold vaccum. I think I have to remove the hub because there is a rear seal on the back side of the hub. I replced the front O ring, but as luck has it, that seal was not my problem