I have done a lot of research on the web and cannot find the problem to my truck! So here's what I have done so far, I have checked the solenoid and thought it was faulty due to a check that I had found on YouTube. So the test I did was: Unhooked the vacuum line, in two wheel drive, engine running, I checked vacuum and the thicker line had vacuum. The next check was to disconnect the check valve from the vacuum line and put it on the vent line to see if the hubs would lock, they did. The next check I performed (vacuum lines back to normal) with engine running and the vacuum line connected, vent line NOT connected, electrical connected, and engine running I had vacuum on vent line and switch to 4 wheel drive after switching I still had vacuum on vent line. For this test I concluded the solenoid was bad ( just a FYI, it was the old style and for $25 for the new style I figured it was good piece of mind) I replaced old solenoid with a brand new designed one and my test came out the same. Now I have checked all of my fuses and relays everything seems to be in working order there, I should also note that the previous owner had done the same thing as I seen all of relays and fuses were checked off in the owner's manual. now my next guess would be the actual switch you turn to put it in 4-wheel drive? Another thing I should mention is that 1.) I bought this truck used from a private party. The previous owner took the truck into the dealership for a brake light illuminated and four wheel drive not working, the dealership gave him a quote to fix a transfer shift motor. I bought a brand new transfer shift motor and installed it, brake light is still on and four-wheel drive is still not working. 2.) I did find and fix a broken vacuum line, it was on the vent side. 3.) I do not hear the typical clicking when turning the **** from 2 wheel drive to 4 wheel drive. 4.) The driver side Hub will need to be replaced as the CV shaft turns with the wheel no matter what test I do, and yes there is vacuum to both hubs/actuators. Passenger side seems to engage and disengage from CV shaft, but I will end up replacing both hubs anyhow.

If anyone can educate me on how I could do further checks on the switch, or other electrical components I would appreciate it! BTW I'm not real savvy with voltmeters so if advice is given to use one please be detailed.

Thank you!