Ok, I was about to place my order for all the seals and o-rings and such so I can service my needle bearings and get my ESOF working properly. I just went out there to take the hose off each hub to see if I could narrow it down to which one was leaking to begin with. Wellllll, I took both off and neither one of them made the air from the vent go to the defrost....

Anyone know which part is causing it not to even begin to get a vacuum going? I checked under glove box to see if anything was loose down there and nothing. I check at the connections at that "place" behind passengers side battery and nothing was loose. It seems like its the pump itself...??

Is there a fuse to this or does it just go bad? Anyone with any ideas please throw them out there for me! Goin on a road trip in Feb and need this taken care of ASAP!!!!

Thanks guys and gals!

Oh yea...Im not switching to manuals only...YET...

 

#28 would be the fuse but if your backup lights work then it is not a fuse that fuse is also tied to the ESOF and brake shift interlock.

 

No offense, but did you have it set to 4wd, key on? (im guessing key on, sounds like you had the heater on) If you didnt have it in 4wd, it will not try to pull vacuum at the hubs, theres a valve.

 

Had mine go out many times and never had a problem with the air vents. Your hubs only use vacuum while switching from 2wd to 4wd or back.
I usually use a hand held vacuum pump to identify leaks and/or determine if vacuum is being pulled at the hubs.

You can have perfectly good vacuum and too much gunk inside the hubs. This will hang up the mechanism and the vacuum will release before it locks into place.

The unfortunate thing about these hubs is that there is a dozen things that can go wrong and then the just don't work.

I have heard that many people want to run out and get warn hubs. My preferance is to disconnect and plug the vacuum line above the passenger fender. If you manually reset the hubs to unlock (ie. remove the hub and press the white plastic piece) you can use this set up exactly the same as the warns.

 

Tristan, If you didn't go to defrost when you turned the switch to 4x4 with the vacuum lines unpluged. You may have a problem with the solenoid that gives vacuum to the fromt wheels. Here is where the solenoid is. Not a good pic, but it is right by the battery on the firewall on the passenger side.

 

Yea...truck was running and 4x4 engaged...

I believe you on the gunk on the inside of the hubs...
I just serviced mine and greased them up not 4 days ago (per guzzles site). Just frustrating....
I hear ya about the white plastic piece. I spent about 10 minutes looking over that hub trying to figure out the operation of them. Its really good idea...just not reliable enough.

 

Ok, this is what I was puzzled about...how do you test/know if this is bad or not?!

 

Ok. Maybe I never noticed my truck going to defrost. If miller says it will, there is probably something to it.
You can try to pull vac at the line coming out of the soliniod. 14-15 psi sustained for about 15 sec should lock in the hubs. 7psi sustained for about 15 sec. should unlock them. If you can't hold vacuum at all then you have a leak.

 

If you have a vacuum pump or gage, connect it to the output line of the solinoid. Should hold 15 going into 4wd and 7 when switching to 2wd.

 

Im pretty sure I have at least one leak in one, if not both. But the bigger problem is the fact that it didnt switch to defrost this time. I dont mind doin the grunt work but If I dont know what to grunt about, Im stuck! That solenoid is kinda freakin my out because I can see the dealer licking their lips already at the money they will charge me! Anyone know the part number or something so I can check out Ed's price on it? Or better yet, a way to test it and see whats goin on with it...

 

If I had one it would make it 2 simple...I wish I did have one!

 

Cheaper than a soliniod.....

 

If you have a vacuum leak on either hoses on the front hubs, your heater or ac will default to the defrost when you switch to 4x4. When I need 4x4 low, I take the connection off the solenoid and no vacuum goes to the front hubs. I do this when I back my trailer into my shop. Slow and easy and I am in 2wd low. I don't know how to test the solenoid, but I am sure there is a way.

 

Miller, thats a good idea on the 2WD Low.
You should at least be able to test functionallity by running a vac line to the cab and switching with you finger on the line.
For my money, a cheap vac pump is the first thing I would throw at this problem.

 

I agree with you on the vacuum hand pump. Good tool to find a vacuum leak. We just need to get through the simple things right now. Good post.