I did some searching this morning both here and in the trucks manual and didn't find the answer I'm looking for.

My question is: Is there a condition or situation when I should "lock" my hubs instead of leaving them in auto mode? One obvious reason is if the auto system isn't working and I can't get the system to engage in auto mode. Is the "lock" feature just a back-up in case of auto failure, or are there other reasons.

All my searching found the posts about the ESOF problems and people swapping out for manual aftermarket hubs…which is another issue.

 

The LOCK feature really is just a backup. For when it positively absolutely has to work.

But I also use it when I am hunting and know I will be using 4WD every day for some period of time. Just so there is one less thing to worry about, and maybe avoid a sticky situation. Some guys leave them locked all winter, for the same reason.

You can leave them locked whenever you want. But I don't like to do that on hard dry surfaces if I an avoid it. You can feel the U-joints binding in a hard turn on dry pavement. I prefer to avoid that little extra abuse.

Interestingly, last weekend I had my rear drive shaft out, and drove my truck a few miles in front wheel drive with the hubs locked. Even though the front diff is open, and there was no rear drive, those front U-joints really bind up a lot on pavement. You can feel the cyclical lock when turning corners.

 

In really cold cold temps I would lock them in as sometimes the coldest of temps will not allow them to turn in the auto position.

Or as Bill does, some extra insurance while in the back country.

I have the manual hubs so I lock mine when really cold and adverse weather is approaching and then I leave them locked the rest of the winter unless I am traveling long distance.

 

Your right about the cold. Mine were not working right in our little -39 cold spell we had last week.
They worked fine before.
So i turned them to lock for a few days.

 

mine won't work in lock and I positively absolutely need it to work.

 

What about your transfer case? You can lock the hubs all you want but if the shifter for the transfer case does not work it will do no good.

 

Lock is for when you need 4 wheel drive, auto is for when you are too lazy to get out to lock them, but if you are spinning chances are auto will fail.

 

Maybe I'm wrong. Probably am. - thought dash switch was for 4x4 hi or low. Period. And the lock on the hubs is for the purpose of failure in vacuum to tell hubs to lock. In response to above reply. No front axle is not spinning when in 4x4. That's why I quoted that funny reply you had.

 

how my dealer explained it to me is that when the hubs are in auto, the truck has to detect slip and then the hubs will engage. the manual position is when you want to absolutely be in 4wd no matter what the conditions are. I tested this theory on a steep snowy grassy slope and sure enough, in auto I could feel it slip for about half a second and then grab hold, in manual they was no slip, it just went up the hill with no delay. so I am inclined to believe the dealers explanation.

 

Wheels don't need to slip, they just need a couple rotations to engage. In fact, if your wheels are spinning, its best to let off the gas before engaging 4 hi or you could break something.

 

You're dealer apparently doesn't understand how the system works.

When you turn the switch to 4WD, the GEM or 4WD control module (depending on the year) first engages the transfer case, then applies a vacuum pulse to the hubs to lock them.

If the hubs are working properly, they are locked at that point. It may take a fraction of second for all this to happen, but no spin is required. If your hubs don't lock in immediately, then they probably need to be cleaned and greased properly.

 

Just to clarify, to test I was already in 4wd, tried about ten times, giving the truck just enough fuel to move and then stopping, then repeating the procedure several more times. never switched out of 4wd until I left the site.

 

I would suggest you take your truck to a different dealer and have a tech that understands the system look at it. Because it's either broken or they made some significant changes in 2011 and did not document them.

 

That sounds more like the traction control available on the new trucks. Has nothing to do with the locking hubs.

 

the wheel slip crap from the dealer is one of two things. either he is talking about the automatic 4 wheel drive like the navigators, or the old mid 80's automatic 4x4. either way it is not the system that is used on our pickups