Upgraded from Tundra so I'm new to superduty. This may sound stupid but can someone explain ESOF to me so I don't break the truck the first month I own it? It has stock manual hubs with lock/auto. My dumb questions are...

If I manually lock the hubs and don't switch the ESOF to 4wd, am I not in 4wd? Also, I was told that in auto hub mode and switched to 4wd that the tires are not locked equally like with an E-locker? The same person told me that if I manually lock the hubs that it is equal to an E-locker.

I honestly think my friend is mistaken and confused me more than before I had asked him. Thanks for the help!

 

Your friend is confused. The ESOF engages the transfer case and auto hubs, if you lock the hubs in all that is doing is locking the hubs with the truck remaining in 2 wheel drive. Newer superduty trucks have the e-locking rear diff option, to engage that you just pull the 4x4 selection **** out, don't need to engage 4x4 I don't think.

 

In auto the hubs work automatically.

In lock the hubs are locked and everything is turning. You are still not in 4wd unless the t-case in 4wd. Locking the hubs manually has nothing to do with torque bias. That is all handled in the front diff.

Manually locked hubs are stronger then when auto locked. It also provides a back-up if the ESOF hub fails.

 

I like how you said "upgraded from Tundra" we love you already

 

I have an 11 4X4 with ESOF. The rear e-locking diff doesn't lock automatically in 4x4. You have to pull the **** out. A little light will come on, saying its locked. It only stays locked from 0-25mph though. It automatically unlocks at 25 no matter what. I have yet to use 4 Lo so I don't know if the e-diff locks automatically in 4 Lo.

 

Go open the Owners Manual and read pages 301-307. It explains how the ESOF system works.

99.999% of the time you will leave the hubs in AUTO mode and just switch back and forth with the dash switch. You can move from 2WD to 4HI at any time whether you are stopped or moving.

NEVER flip that switch while the rear tires are spinning faster than the front tires unless you feel like replacing your transfer case or any of the other front drive components.

Also, if you are stuck and the traction control cuts power, stop hitting the pedal and hold the brake. Then reach over and hold the traction control button on the right side of the Radio/HVAC controls and it will disable ESC/AdvancTrac allowing the tires to spin freely and not cut power.

No auto diff lock in 4LO. The only way for the rear E-Locker to work is to pull the switch out and stay below 20 mph.

 

Apologies for reviving an old thread, but I wanted to search and read some prior to starting a new one. I’m new to these trucks and ESOF.

Are you supposed to be sitting still when changing between 2WD/4WDH/4WDL? Or is the truck supposed to be moving at some recommended speed?

Reason I ask is, I was cleaning the inside of my truck this morning and didn’t recognize I had accidentally rotated the dash **** to 4WDH. When I went to back the truck out of the drive and then go forward it acted as if it didn’t want to move or was slipping. Then I noticed it was in 4WD so I stopped and changed it back to 2WD before I drove it anymore.

Just want to make sure I didn’t damage anything.

 

2wd to 4wdh and 4wdh to 2wd are shift on the fly. Meaning you can be setting still or moving Just not spinning. To change in or out of 4wdl you have to be setting still and put trans in neutral for it to change.

 

👍🏻 Thanks.

 

You also have to have the brakes applied setting still to go into 4Low AFTER your 4hi light is illuminated

 

Reviving this again, but for a different question. What is actually happening with the transfer case and front differential when in 4x2? I assume they are just free spinning. The reason I ask, is my 2015 just crossed 200K miles and its time to to change the rear differential fluid again. I have engaged the front differential a grand total of one time for about 1/4 mile in 50K miles. My gut tells me there should be nothing wrong with the transfer case fluid or the front differential fluid. What is the general consensus here?

 

When in 2WD with the hubs in either the Free or Auto setting (depending on if you have ESOF or manual 4x4) the front axle and driveshaft should do very little if any spinning. It would be worthwhile to check the level of the front differential fluid, but with that little use it should be in very good condition unless there has been water intrusion for some reason.

I would recommend changing the transfer case fluid though because there are parts spinning in the transfer case at all times, even when you are in 2WD, to transmit power to the rear driveshaft. The transfer case fluid change is a simple drain and refill using the two 10mm allen head plugs in the back of the transfer case. If I remember correctly the transfer case takes just over two quarts of fluid, but you can verify that in your owner's manual.

 

Old school best practice is to engage 4wd at least once a year to stir up the front diff oil and keep the u-joints flexy. This also seems to really help all the unfortunate folk with electric shift t-cases as it keeps the t-case motor from seizing.

Your t-case is pumping ATF any time you're moving regardless of drive position. It's just a crude eccentric pump but that's all that's needed. So yeah, the fluid in the t-case doesn't know or care how often you use 4wd, it's 100% duty cycle like the gear oil in your rear axle.

And while this applies to earlier, necro'd replies: if you're fortunate enough to have the weird lever thing on the floor, the rear locker switch is rotary, in place of the ESOF switch (ie you don't pull, you just turn)