I’ve read many posts about ESOF and fault vacuum lines – and how that will prevent 4x4 from engaging. I experienced a different problem this past weekend, so I’ll post.

Here’s the situation...

I took the fam out to get our Christmas tree. Was about 1.5hr drive up to the mountains. Outside temp when we left the house: 10’F. Outside temp when we arrived at destination: 9’F. Quite a bit of road grime on the way up from sand, slush, and that magnesium chloride (or whatever they hell they put on the roads in an attempt to keep it from freezing). 4x4 worked fine on the way up. 4x4 light on dash was on, and I KNOW I could not have climbed the snow-covered forest roads without being in 4x4. Also, I could hear and feel the front hubs turning.

On the way home, once I got to where the roads were sufficiently ice free, I turned the dial on the dash back to 2WD. 4x4 light goes out. But I can hear and feel the front hubs are still turning. Toggled the switch back and forth a few times. 4x4 light would come and go with the toggled switch. But the hubs didn’t disengage.

When I got back into town (outside temp now about 5), we stopped at a red light and I toggled the switch again. This time, the hubs disengaged.

Is this a sign of bad vacuum? Or more an indication of faulty hubs??

Input is very much welcome.

 

I would say you need to service your hubs as it sounds like they are sticking. I had the same issue and got sick of not knowing if they were going to unlock or not. Usually on mine it was either one side our the other that would not disengage. My solutions was to get rid of the vacuume hubs and install some Warn manual hubs. No more sticky sticky..

 

I think the manual states that you "might" have to back your truck up a minimum of 10 feet to assist in disengaging the hubs. Sometimes they will disengage without backing up.

 

This issue was most likely caused by the extreme cold and not stopping and trying to back up.

While you really don't need to back up when going 2 hi to 4 hi and back again..sometimes it helps to release them.

 

Ok, thanks. I'll Google front hub service and get after it.

 

Look in the TECH FOLDER.

 

From the owners manual:

Shifting from 4x4 HIGH (4WD High) to 2WD (2WD High)
Rotate the 4WD control to 2WD at any forward speed. Disengagement of the transfer case and front hubs may be delayed due to torque bind which is caused by driving on dry hard surfaces or performing tight turns while using the 4WD system.

• You do not need to operate the vehicle in R (Reverse) to disengage your front hubs, but it will eliminate any torque bind and allow the system to immediately disengage.

 

Hub servicing looks simple enough. Hope to knock it out in the next couple of weeks.

Regarding Warn manual hubs...it's my understanding that removing and capping the vacuum lines basically turns the Auto/Manual stock front hub into a Warn-like manual hub setup?

Regardless I hope to get the auto ESOF fixed, as I like the system very much...when it's working.