I have a '99 F250 7.3 4 x4 with the electronically activated four wheel drive. You know the one with the switch on the dash. Has worked fine for 7 years until recently. Now I have to get out and lock the hubs in manually to get into 4 x 4. The electronic switch no longer works. Anyone else had this problem? Does this require a simple electronic component replacement? Thanks for your help---

 

Have you taken apart the hubs, and cleaned and lubed them?

 

When you say the electronic switch no longer works, do you mean that the light(s) do not show in the dash - or do the lights work, but the hubs don't lock?

 

Well he needs to understand how his 4x works. If he can get out and lock the hubs manually and have 4w, the switch is working.
Whats not working is the vacumn actuated hubs.
He needs to chk the fuses first,Then vacuum lines to the hubs. If he has the vacuum pulse through the vacuum line,he then can be sure he needs to rebuild or clean his hubs.There are o-rings inside that seal the vacuum to lock the hub in.

Also do a search this has been beat to death already and winter is coming we will be swamped with these post soon.
Rich

 

I agree but I would just check the vac. lines to the hubs first. Easy to see and quick check. Probably broken vac. line. Cost me $4.29 to replace my lines. Even if the hubs are sticking they would probably work but good maintenance to follow tech section to clean hubs at least every 3 or 4 years " but your mileage may vary " I have replaced vac. lines and cleaned hubs and mine work great. The vac. system is reliable. Jim

 

Yeah - seems like we need a Mod that ain't skeerd to post a sticky about it...

 

Time for a FAQ on ESOF

 

Thanks to F250WHEELS, BIG ORN, FORTYFORDS, AND VETTDVR for the help. Following your direction I quickly found a vaccum line disconnected due to the rubber tube cracking from age. Cut a new end and reconnected and it works fine. Will do the recommended maintanence, including changing the rubber lines, next. Thanks---Roger in Elk Grove, Cal

 

ESOF (Electronic Shift On the Fly). Means you can go from 2wd hi to 4wd hi or vise-versa while moving (or on the fly). You must put your truck in Neutral to shift into 4wd low (since it involves a different gear in the transfer case).

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When you turn your dash ****/switch from 2wd hi to 4wd, several things happen:

The motor on the transfer case 'basically' connects the front drive shaft to the transmission. Thus, now the front drive shaft turns in unison with the rear drive shaft. And now the front axle turns with the front drive shaft.

Sensors at the transfer case 'basically' sends a signal to your 4x4 & LOW RANGE lights on your dash board. Now this is where it can get confusing - the dash lights do not indicate whether the hubs are locked or not. So you could have a 4x4 dash light on but your truck is not in 4x4. Or you could have a 4x4 dash light off but your hubs are still locked. Unlike the new auto/lock hubs - when you have problems with the transfer case motor not working, you are not going to be able to override it to put it into 4x4 (this is probably the biggest gripe people have about the ESOF system).

The hubs 'basically' connects the front axle to your front wheels. This system uses timed vacuum sequences to lock and unlock the wheel ends. A high vacuum level is used to engage the hub locks, and a lower vacuum level is used to disengage the hub locks, after which the vacuum is released and the hub lock holds itself in the proper mode. The vacuum signals are supplied to the hub locks by system components, including Generic Electronic Module (GEM), wiring harness, solenoid, vacuum harness, and vacuum seals. Some 'noises' (suck as a click/clunk/thud etc.) during hub engagement/disengagement is normal. As a first step in service, eliminate such obvious items as loose wiring connections, loose vacuum connections, or damaged vacuum lines. On newer auto locking hub systems, you can override them by turning the selector to "manual" when you have problems with the auto lock feature.

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WHY ESOF FAILS - The biggest problem people have from ESOF systems (believe it or not) is under-use. They only use the system 1-2 times a year when it is slick outside. Then it will go several months without being used. Do yourself a big favor, at lease 1 time a month (even on dry pavement) - on a slow short straight away area - engage and then a few seconds later disengage the system. Do not go very far, fast, or turn on dry pavement with truck in 4x4 or binding of the drive train could occur. Also, every now and then, rotate your AUTO/LOCK hub selector back and fourth to keep it moving freely.

MANUAL OVERRIDE - The newer AUTO/LOCK hub locks have manual override selector dials which makes them (at a quick glance) look the same as the non-ESOF hubs with the LOCK/UNLOCK selector. When rotated to the "lock" position it will keep the mechanism locked regardless of the instrument panel 4X4 mode switch position. For the most part, keep them on the "auto" position.

The older auto hub locks do not have any kind of override selector dial.

HUB DISENGAGE TIME - "Slow" release of the hub locks is not considered abnormal for this system according to Ford TSB (Technical Service Bullitins). Anytime vacuum is applied to the hubs, whether for 4X4 or 4X2, the hub locks will initially engage. If 4X4 was requested, they will remain engaged, but if 4X2 was selected, the internal mechanism will release only after the GEM timers expire and vacuum is vented from the hub. This normally takes 15 seconds, but can take up to a whoping 2 minutes depending on how the 4X4 mode switch was operated. After the hub mechanism releases, internal springs must work the hub lock gears to the disengaged position. Road bumps, vehicle speed, acceleration cycles, or momentary reversal of direction can assist this process, varying the length of time the hub locks remain engaged in each situation.

MATCHING HUB PAIRS NOT REQUIRED - Left and right side hub locks are not connected other than by the common vacuum supply line. If a malfunction in either hub lock is diagnosed, it should be replaced as an individual unit; there is no need to "balance" an axle with new hub locks on both sides. If both sides appear to be malfunctioning, be sure to verify upstream system integrity before replacing both hub locks.

HUB LOCK REMOVAL - After removing the hub lock retaining ring, be sure not to use tools other than hands or "grip" gloves as damage may occur to either the paint or function of the hub lock. Pliers or channel locks should be only considered as a last resort as they will usually damage the hub lock, making replacement necessary.

HUB CONTAMINATION - If contamination (water, mud, etc.) is found in the hub cavity, look for the source. If it is due to system leaks other than the hub lock, they must be found and repaired. Always replace the hub lock O-ring before re-use.

TORSIONAL FAILURE - If a torsional failure (twisting fracture) of the hub lock is suspected or the internal gears are "shattered", the axle constant shaft may have been damaged as well. Inspect the axle shaft carefully; if twisting has occurred at the base of the axle splines, it is difficult to see without removing the bearing assembly.

RATCHETING - If a "ratcheting" noise is found especially over road bumps and potholes, suspect the needle bearing that supports the inboard end of the axle constant shaft within the hub/bearing assembly. Eliminate this as a cause before servicing the hub lock. Wear at this bearing can set up vibration, which may be heard as ratcheting, while a seized bearing can bind the shaft, forcing it to rotate in 4X2.

Hope this helps, I could go on.....

 

I too am having a problem with my ESOF on a 2000, PS, 4X4, 202K. My dash light light up on start, but when I turn the switch it does nothing. I drove 32 miles to work with the switch on and never locked into 4x4. I have vacumn at the hubs, would it be the shift motor on the tranfer case, also about the time I noticed the 4x4 not working my cruise also stopped working. Any Ideas.

Don

 

when u take the auto hubs out, iv notest u dont have to take the wheels off. so with that said, could u still drive the truck around temporarly while the auto hubs are out, right? like work on rebuilding the auto hubs after work, but still be able to drive the truck to work every day? or just slide in some aftermarket locking hubs while the auto hubs are in the prosses of being rebuilt?

 

If you were to close off the open end of the hub you could drive it. You would not have a/c control if you turned 4x4 on. The hub is not Load bearing only transmission of power when engaged. So my opinion is YES you could drive it buy why? It only took me about 2 hrs to clean and reinstall both hubs. So why drive it, just clean lube and reinstall. Buy new o rings before you start. Jim

 

get the new O rings, ok. i did check for vacume last night, got some suction on the driverside, but nothing on the pasenger side. im going to look and see if i have a bad hose on the pasenger side. and also i cant remember wich side it was, but one of the sides turns hard. it turns but its pritty hard to turn. so im sure that side needs to be pulled. and now that i think about it i believe it could be the passenger side that is hard to turn, and probebly because its not getting vacume and hasent been used in a while? i guess?
i know there are some good instructions on here on how to rebuild these auto hubs. i just got to find that link again. i think it was done by one of the members on here.

thanks vettdvr..


Brian.

 

THIS IS GOOD....