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First snow of year, and my '05's ESOF wouldn't lock into 4x4

4K views 41 replies 8 participants last post by  Godzillamax 
#1 ·
We got a few inches of snow this morning and my truck (2005 F250 6.0 superduty diesel FX4) wouldn't lock into 4x4 so I couldn't even get up my driveway (which only has a slight grade to it) after driving the kids to the bus. I tried manually locking the hubs but even that didn't put the truck into 4x4 and the wheels were just spinning in the snow.

After plowing with my 4-wheeler I was able to get the truck into the garage and test the ESOF system. Sure enough there was a vacuum leak (did the vent test). I used my vacuum hand pump to test the ESOF system and everything held a vacuum except the hubs.

So, either both my hubs are shot or its just the hub seals. But since putting the hubs into manual 4x4 did nothing I'm leaning towards the hubs being shot.

Anything else I can check before buying new OEM auto hubs from the dealer at $212 a piece?

Thanks in advance!
 
#3 ·
Just for sh!ts and grins. Lock the hubs in manually and leave the truck in 2wd. Crawl under the truck and try to spin the driveshaft
 
#7 ·
Did this. Truck was in park, key on (but engine off), and I could manually rotate the drive shaft. I then manually locked in the 4x4 hubs (ESOF switch in truck set to off) and the driveshaft locked (or at last only had about 1" of play in it). I did the same test with the ESOF in the truck switched on and the driveshaft locked (with about 1" of play in it).

So, what does that mean? Because when I manually lock the hubs and drive the truck definitely is not in 4x4.
 
#8 ·
Sounds like the tcase is not engaging. Back to heavys idea. Relays. This is out of my realm so I'll leave it up to heavy.
 
#13 ·
Even though they click they can still be bad. I would swap them with known good ones first.
 
#17 · (Edited)
I checked the motor casing and it looked to be in great shape (clean, no leaking or rust or corrosion on it or the seams). I pulled off both connectors (one on the top, and one on the bottom), and both looked like new (no corrosion, signs of wear, etc.).

When you say listen for movement is that with both connectors on, the key in the on position and the engine off, and then engage the ESOF by switching in to 4hi?
 
#19 ·
With the engine off, key on, turn the 4X4 knob and listen very carefully. Do you hear the shift motor actuator move? If not, check fuse numbers 19, 27, 45 and 33 in the CJB (fuse box under the dash). This assumes that your relays are good..by the way
 
#21 · (Edited)
Okay I did this test and here are the results. First, it takes a long time for the vacuum pump motor to stop running (like 1 minute) after key on. Once it has stopped running, and with the engine off and key in the on position, I switch the ESOF to 4hi (this is with the hubs in the auto position). I hear a click in the engine compartment (the ESOF relay), and then what sounds like a electric actuator moving. This sounds (electric actuator) comes from the engine compartment and I'm pretty sure it is the PVH solenoid actuating. Turning off the ESOF I hear that electric actuator noise again.

I tried to turn on the ESOF and get under the truck to listen to the transfer case electric motor for noise, but didn't hear anything but also couldn't get under the truck fast enough. When my wife gets home I will get under the truck and have her flip the ESOF switch so I can listen better. In the meantime, I will check the fuses.

Edited to add: I checked the fuses you listed, they were all good.
 
#23 ·
Correct, but I think the vacuum system is a secondary problem that I will need to eventually fix. When I tested the vacuum system at each wheel (from the rubber vacuum line connector that connects to the hub) back up to the main vacuum system it held vacuum perfectly on both sides. But when I tested the vacuum of each hub (short vacuum line connecting to the hub) both failed to hold any vacuum at all. At minimum I probably will need to pull each hub and service them and add new rings/seals. But that is secondary to getting the 4x4 working first.
 
#27 ·
I meant how did you get her to help, I can't ever get any help.
 
#30 ·
Yup. Couldn't get up my driveway this morning (tires were just spinning and spitting snow out the rear and I began to fishtail). After the ESOF was switched to 4x4 and it didn't engage (I even tried reversing to see if it would kick in) I got out and manually locked the hubs. 4x4 still wouldn't engage.

I'm wondering if the internals of the transfer case shift motor (gears, etc.) might be bad. So it gets power and actuates, but can't shift the truck into 4x4.
 
#31 ·
Ok, I have this same issue...but with an added twist.
A few weeks ago, I had an issue with my 4 wheel drive. When the engine is off, I can hear the actuator, I also have a failed hub seal (someday when I have time I will get to it) and although I manually lock my hubs, it still takes an extended period of time for the transfer case to engage...but it does engage. It just takes a few minutes. Flip it in neutral, flip the switch with the hubs engaged...and wait. Try 4 low.
Do you have any other, seemingly unrelated, issues with your truck?
 
#33 ·
UPDATE!

This morning I awoke to fresh, wet, snow and debated driving the kids to the bus stop in the truck vs the 4 wheeler. I opted to try the truck again and started it then manually switched the hubs to 4x4. After the trucked idled and warmed up I drove it and it was in 4x4!!

So, few possibilities?
1) Relays are working, but inconsistently
2) Transfer case electric motor is working/actuating, but inconsistently
3) Gearing inside the transfer case (that the electric motor actuates to put into 4x4) is working, but inconsistently
4) Something is wrong causing a delay between manually switching the hubs into 4x4 and the truck going into 4x4
5) Any combination of the above

Anyone have some thoughts? I'm going to start out by replacing both relays (since they are cheap), and then servicing the hubs (since I know they fail to hold vacuum).
 
#36 ·
replacing both relays (since they are cheap),
servicing the hubs (since I know they fail to hold vacuum).
That is where I would go.

Two thing to remember, not all relays are created equal so get the higher end option.

Servicing the hub usually doesnt mean replacing the seals and o-rings... contact @fordsvtparts to make sure you have what you need.
 
#34 ·
Not directly related, but when I rebuilt the t-case in my son's Explorer, I noticed that the electric motor is easily removable and replaceable. Disregard the arrow and look at the top of the pic with the wiring. Does your transfer case motor look like that?

 
#35 ·
Not directly related, but when I rebuilt the t-case in my son's Explorer, I noticed that the electric motor is easily removable and replaceable. Disregard the arrow and look at the top of the pic with the wiring. Does your transfer case motor look like that?
Yes and no. Same structure, just looks a little different. Here is mine:


Also, I took a quick drive and manually locked the hubs into 4x4 (heard the transfer case electric motor actuate) but the truck's 4x4 didn't engage. after driving around the block (hubs locked, but no 4x4) I then switched the ESOF into 4hi (with the hubs already manually locked) and the 4x4 system engaged.
 
#39 ·
Thanks. I'm going to start with installing two new relays and servicing the hubs (clean them, new o-rings and new grease). Shouldn't be more than $50-$75 for relays, gaskets, grease, etc., and since the truck is 10 years old and this has never been done it's time to do it anyway (it was probably time to do it long ago, but time escapes).

If that fails to solve the problem my next step will be to replace the motor on the transfer case (still the original).

I called the dealership this morning and asked how much would it be to grease the autolocking 4x4 hubs and add new o-rings. They said they no longer give over-the-phone estimates, but since I have been a customer there for sometime she said it could run anywhere from $500-$800.

Found this guide :Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
And this YouTube video:

And it doesn't look too difficult (famous last words, eh).
 
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