The colder it is, the slower my ESOF happens. Over the past winter, my truck got to the point that I could not shift into 4WD high until I had driven at least 5 to 25 miles. In warmer temperatures I still have a problem at times. What I mean by long is this:

• I generally put my 2004 into 4WD hi every time I drive up my gravel road driveway. So I watch for any problems.
• In warm weather, it takes 10 to 60 seconds mostly, but on occasion it can take longer to engage, especially lately.
• I think the hubs are locking, but it is the transfer case not engaging which is what turns on the amber 4WD light... so I am watching the light and listening for the "clunk" to know for certain.
• I don't slow down to shift. I am normally driving 20 to 40 mph.
• In winter and when driving in snow, I would engage the 4WD as soon as I drove a few feet. Since it would not engage in the cold, I reverted to flipping the switch back to 2WD until I felt like trying again and again, until it engaged. I sometimes would try every 5 minutes or so. I would try leaving the switch in 4WD, but I could drive it 15 miles with no amber light.
• To avoid the problem with cold ESOF, I also reverted to leaving the truck in 4WD overnight. When I started the truck, the 4WD was still engaged until I turned it off.
• It never hangs going back to 2WD. It usually shifts in 5 sec or less.
• I have rarely if ever heard it do a rough shift into 4WD.

My possible remedies...

• Is it a solenoid or relay?
• A motor? An actuator?
• Old transfer case oil?
• Worn parts or springs?
• There isn't a thermal actuator like those cheap Shevies I hope?!
• Is there a TSB about this or does the Haynes manual cover any of these parts?

And please, folks, this is not an operator error here, the truck is broke. After all, it eventually works during the daytime when it's warm, but on cold mornings it is sluggish at its best.

 

Have you turned your Hubs to the Lock Posistion and tried 4x4 that way ?

Seems like most problems with ESOF is the Hubs losing Vacum to actuate them,,,Start with simple stuff first,,,,just what i have read,,,,My SuperDuty is Manual shift T-case,,,only way I would buy a truck !!

 

The hubs won't even try to lock until the transfer case is engaged (known by the 4x4 light), so your problem is not hubs (yet).

I would speculate at two most likely problems. One is one of the relays not making contact in the cold, the other is the shift motor being gummed up and not wanting to turn in the cold.

The relays are cheap. It might be just a cheap fix to replace them and see what happens. About $20 each and there are two. They are in a box under the hood on the drivers side. They are the only two identical relays in a box. The box is usually wrapped in fabric electrical tape from the factory. Every other box has more than 2 relays, or different shaped relays, or a fuse, or something else.

The shift motor might be harder to diagnose. The only thing I can suggest is to wait until it is really, really cold, take it off and put power across the pins on the 2 pin connector. Carefully and only for a very short time, and see how well the motor turns.

 

Ok I will test or work with the relays as I can do electrical repairs. Why 2 relays? Anyone seen a relay that doesn't work when cold?

As for the shift motor, I want to know a little more. Is it bigger than a breadbox? Is it accessible without messing with the front axles or transfer case? If I can remove it easily, maybe I could test it or put it in the freezer. Will it be obvious what its polarity is by wire color or markings?

This is sounding like it could be a lot cheaper and easier than I thought or I would have done this even in a cold shop last winter. Or at least that is my story.

Thanks for your hand holding here!

 

I can't say I've ever heard of a relay not working in the cold, but I suppose anything is possible. Attached is a wiring diagram of the relays and shift motor.

Essentially, the common wire of each relay goes to one pin on the motor. Both are normally held to ground. When a relay is activated by the control module, one pin or the other gets power. Power in one polarity moves the motor one direction (2WD to 4WD to 4LO) and power in the other polarity moves the motor the other direction (4LO to 4WD to 2WD).

Part of the shift motor assembly is a set of switches that report back to the control module the position of the shift motor and whether or not it moved when it should have.

The shift motor is on the transfer case and has two connectors. One 2 pin connector for the motor power and a 6 pin connector for the switches. It is held on by 3 bolts and is pretty easy to remove.

 

Wow, thanks. I pulled off the 2 relays and they are the absolutely most common and cheapest automotive relays possible. They cost about $5 at many parts stores if you can get a counter guy to go hunting generic relays for you. Anyway, I have a few spares I am sure so I will try this possibility... but I think it is going to be the motor.

Oh, do you know where the ESOF solenoid is? That may be good to know about. I have a feeling it might be near the relay box? Or by the Four-wheel drive control module?

So I can try:

1. Relays
2. Shift Motor
3. Solenoid
4. Four-wheel drive control module
5. ECM

That was sorted on the ease of checking and the likelihood of an item being broke. It's probably the motor.

 

The ESOF solenoid is on the passenger side firewall towards the front. It provides a vacuum pulse to the hubs to lock and unlock them. The control module will not attempt to lock or unlock the hubs until the shift motor switches have indicated the transfer case shift is complete, so it is unlikely part of your problem.

The 4WD control module (2003 and newer) is behind the glove box.

The engine computer isn't involved.

 

It must be my motor. I am now reverting to beating on the transfer case while I wait for the light to come on. I have had some success doing this, but obviously a pain. Changing out the relays had no effect as far as I can see. Need to pull that motor, I guess.

 

Did you end up getting this fixed? I have same issue and trying to figure it out.

 

Not yet. I am good at procrastinating, so feel free to hijack the thread and someday I will get to this issue myself.

 

Hi. Original poster here. Strangely enough, this problem fixed itself. This past winter, as many of you may recall, was pretty cold weather for the eastern half of the US. Well, I didn't have any 4WD shift problems with my Excursion. Now, I don't think I drove it all that much, but the light came on in about 5 seconds when I clicked over to 4WD Hi. I was wondering if I should change my motor still, and I found my old thread. (I didn't realize it was this long ago I had this problem.)

The relays didn't do anything because I still had problems. I think I will just change the transfer case oil and skip the motor replacement unless this happens again.

Incidentally, here are the part numbers for this repair.

Dorman part #600-805 (new)
replaces Ford factory OE # YC3Z-7G360AA
A-1 CARDONE Part # 48205 Reman. (may need a core)
RETECH Part # UMM4473 Reman. (may need a core)

And there are lots of used ones on eBay from F250 and F350 Superduty trucks. Going price for all of these is $75 to $125 right now.

 

Very interesting, I'm glad you came back for an update. I don't think the T-case lube would have anything to do with it, it's just relatively thin ATF. But stranger things have happened though, let us know how it works out!