Esof? Vacuum leak is pretty common. Does the vent go to defrost when you turn on 4x4?

 

Need to try that. It was already on defrost. Low here is 5 tonight. Don't want to go start it just for that now. Will try tomorrow

What is ESOF? I have an old diesel Mercedessi I am not unfamiliar with vacuum but this is new territory for me.

Tks

 

The 'auto' hubs are vacuum operated. Did you have them manually locked?

 

ESOF = Electronic Shift On the Fly
The switch on the dash controls the transfer case solenoid and the vacuum module that sends vacuum pulses to the hubs to engage and disengage them. If there is a leaky hose, the hubs won't lock or unlock automatically.

 

Gotcha. Tks. Hubs were locked. Had used 4wd earlier, we have a 6" snow on the ground so I locked the hubs a couple days ago.

 

If you have forscan it'll conduct a self test and flag errors and point you in some kind of direction.
I need to check mine as well because I encountered the same issue the other night.

 

easy way to see whats going on

try and turn the front drive shaft if it is locked

reach in to the knuckles and see if you can turn either axleshaft

 

Not to jack this thread but my { 4 Low } seems to take a long time to go into low. Is there anything to grease or oil on the gadget that moves the transfer case selector shaft gizmo lol

 

I would check out the relays. They're located near the drivers side battery. There are 2 relays. One shifts in and one shifts out. Switch them and see if it goes in.

k

 

Update

Started truck last night and switched to 4wd. It did not switch to defrost so I assume that implies this is not a vacuum issue.

Drove a little ways tried again and it did engage, even 4Lo. Drove a little further, tried again and it didn't engage. Guess I have a gremlin somewhere. I have an Edge CTS, forgot to look for codes.

I still need to try to turn the driveshafts as was suggested, but I am suspecting that the "motor" on the transfer case is on its way out.

Also I did have a TC replaced just prior to this, but ESOF worked fine for 2-3 days after getting it back so I tend to think this is a coincidence. TC had a crack in a weld and was causing a really bad leak.

 

Mine was the 4x4 vacuum switch under the hood (passengers side fender). I took it apart and the sponge filter inside was old, degraded, and clogging the vacuum ports so the hubs wouldn't get the vacuum. I cut a new sponge out for a filter and replaced it. They only cost about $30 for the whole part, but I had the sponge laying around anyway.

 

Does it work when you manually lock the hubs?
Mine didn't go into defrost either when I flipped the switch, but the 4x4 lights up on the dash.
But when I manually lock the hubs, works perfectly.
I'm going to run forscan and see what it says. Maybe a solenoid or relay like was Said

 

I had issues last year, turned out to be the hose from the pump being cracked. I need to check mine to make sure it's still working.

 

This has me wondering if a vacuum line is my problem too. I had an unfortunate occurance early this week where I stopped on the side of the road to let a person who wouldn't move from the middle of the road to pass. There was ice everywhere. While I was stopped my truck just started to slide to the right. I was in 4whl and tried to drive slowly forward and to the left but I just kept slipping to the right. Ice doesn't care who you are or what you drive! When a buddy was trying to pull me out the back right wheel was the only wheel that spun. It eventually took a tow truck to pull me out. At least the tow truck had a 6.0 so we kept it in the family.

 

I get a kick out of the truck parked next to the fire hydrant. My luck I would also get a ticket for doing that. I know a buddy of mines truck had a bad hose by the vacuum pump on passenger front fender. Only takes one hose off and nothing works so look over all the hoses all the way to the front wheel hubs.

You should pull the rear axle cover plate and clean up the pumpkin and inspect it for metal etc. May be just a matter of needing new fresh oil in the rear axle to get the posi-traction back up and running. I didn't put any of that Ford slip crap in my axle when I changed it in my truck. Ill take a little chatter over no posi-traction.

 

I get a kick out of the truck parked next to the fire hydrant. My luck I would also get a ticket for doing that.

I was worried about that too. At one point the truck was leaning so bad (more so than in the pic) that I was worried it would roll onto the hydrant. Thankfully the tow truck guy was a pro and got me pulled out without any damage.

 

Definitely keep us posted. I switched to 4WD a few days ago to get out of a saturated front yard. Only to find the front wheels weren't turning still, and like everyone else, dash showed 4WD was on. SO, got out, manually locked the hubs, and all worked. I haven't checked to see what the issue is, but I'm assuming it's a vacuum line.

 

Same problem here. I am about a grand deep on this one now. Here are the parts that could be an issue if it works with the hubs in manual but not in automatic.

- Dash Switch - haven't changed mine seems OK
- PCM? One part of the computer sends the signals to the ESOF solenoid and the transfer case relays. Mechanic tested seems OK on mine
- Transfer case relays - my transfer case is 100% OK, may be your problem though. Cheap easy fix
- ESOF solenoid - I am on my 4th one. Original was bad, dorman one was bad, ford one failed in 2 months, on another ford one. Now the mechanic indicated this was the issue last time and so I got a replacement for free from ford. Unfortunately after a week, 4wd failed again. I don't think this is the issue.
- Vacuum System. You need to have a functional vacuum pump, integral lines, and vacuum tank. If you have a failed vacuum system your heater will not leave defrost or will switch to defrost when you select 4x4. I had bad vacuum pump and failed ESOF and bad ESOF which caused vacuum leaks.
- Vacuum lines from ESOF to hubs. I have replaced the sections from the axle to the frame with silicone ones as mine were falling apart. Did not resolve the problem
- Hubs - Both of mine failed and were replaced. Mechanic indicates mine pass vacuum hold test but I am suspicious they did not rebuild everything correctly here. i will repeat the vacuum test myself once the temperature is back above 10. i need a bigger garage, this monster doesn't fit in mine!

With a mitivac you can troubleshoot a lot of this system by just hooking it in line with the vacuum lines and watching what the system does. There are a lot of articles on here about that.

Good luck, please post what you find on here it may help me and others.

 

Someone needs to post a sticky on what to when your 4x4 doesn't work, and how to check if it is your hubs or transfer case that's not engaging. The 4x4 systems basically work the same way from the 99 to current trucks, and this is a constantly reoccurring topic.

 

There are 42 pages in the Super Duty Workshop Manual for trouble shooting the 4x4 system. Someone here has a link to download it. I have it but could only email it. If anyone needs it I can try to email the PDF.

k

 

Not to thread jack... is my 07 f350 esof? It's the king ranch loaded... I'd assume but I'm afraid to try it.


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If it has as switch it is esof if it has the lever it is msof.

 

So esof?


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Yes.

-jokester

 

yes you have the esof. same as mine

 

Thanks for all the comments . No update to share just yet, been on other projects. The relays I did take out and they looked fine, I did not switch them though, didn't think of that . The vac pump / filter that was mentioned earlier - where is that, can someone post a pic?

The solonoid is my suspect at this point., based on research and such. Anyone got a part number for that? Is this the same as the "motor" I have seen online, attached to the transfer case?

I did have a new TC installed right before this started, but it worked fine for a few days afterwards, so I am thinking this is unrelated and coincidental. I also need to find a place to try it out - don't want to tear up the yard figuring it out.

 

I replaced the solonoid in my truck last summer. The solonoid itself had a small crack in it and was leaking out.

I ordered the part from Autonation Ford it was about 60 bucks, give or take. Not saying a knockoff wouldn't work, I just have better luck with genuine parts. @fordsvtparts

The vaucuam tank, pump and solonoid are all on the passenger side fender by the engine.

7C3Z*9H465*A

 

mine is a bit dfferent but being esof it still doesn't work :doh:
i have replaced the 4x4 module behind the glove box the switch in the dash, the shift motor on the tcase and still the lights flash on the dash at startup but will not remain on or lock in.
so I have to crawl under shift the tcase with a crescent wrench and lock the hubs manually and i am off to the races
or at least i can get out of the dirve way :rofl:

I have the forscan but have not even used it yet ..
i gotta get into that and see how it works :nod:

 

If your 4x4 light isn't coming on when you engage the switch, it could be the relays under the hood. I have that happen to mine to. No 4x4, no light change. Relays were corroded.

 

replaced both to no avail.
but thanks that was my thought at one point as well