I've been looking through threads about this issue and there's plenty but all the ones I check don't have any solid conclusions. Here's my issue:

I have a 2001 F250, 7.3L with the auto/manual hubs and the 4wd dial on the dash. The other day I tried engaging the 4WD but it would not engage. My hubs have not seemed to work on auto very well so I usually turn them manually. I did this and still nothing, no light on the dash. For a while now when it was working I would hear a high pitched squeak or squeal until the 4WD engaged then if I was in and out (using the dial) it was fine until it sat and got cold. We got some snow the other night and I decided to check the fuses as I wanted to use the 4WD. I checked both under the dash and under the hood, nothing blown. When I got back in and used the dial the 4WD came engaged (hubs were turned to manual) and the dash light showed 4X4. The truck sat overnight with the 4WD engaged (I live one a farm so my driveway doesn't always get plowed). This morning when I went to use it the dash light, 4X4 was off even though the dial was still in 4H. Squeal still present when starting out, turned the dial to 2H and the 4WD wouldn't disengage. Turned the hubs from manual to auto, nothing. Drove backwards for a ways, pulled both fuses again (still okay), played with the dash dial some, no chages. Nothing seems to be working and the system is still in 4WD. I haven't noticed the defroster staying on all the time but it's winter and i only use the defrost or foot and both work fine. I'm suppose to drive to Omaha Sunday and would, at the very least, like to have the 4WD disengaged. Any help would be much appreciated.

 

Cant help with conclusion, but a "band-aid" approach, is maybe disconnect the front driveshaft?

 

Is there oil in the 4wd transfer case?

-Joe

 

Are you having trouble with the X-fer case not shifting out of 4wd or the hubs not disengaging? Or both?

 

Sounds like both, the squealing is probably coming from the transfer case but if he turned the hubs to auto and its still in 4wd then that is an issue too, right?

Joe

 

Sometimes if the front hubs won't disengage you can turn them back and forth between auto and lock a couple of times and end at auto they will disengage. If they still don't disengage after trying this turning the axle will sometimes will disengage it. Even rocking the truck back and forth can help.

You can also free the hub by pulling it off. See Guzzle's Auto Hub Lube for removing the hubs and dissasembly. Also, since doing this entire dissasembly and lube procedure my hubs haven't stuck.

If the X-fer case won't shift you can pull the X-fer case shift motor assembly and manually shift the X-fer case to 2WD position.

 

I believe the problem is in the transfer case. When I switch the dial on the dash I don't hear anything happening. I've even tried putting it in low 4WD but still nothing (truck in neutral and foot on brake). How do you pull the transfer case shift motor and manually shift it to 2WD? Will I need to catch Tranny fluid? Once it's off, how do I "shift" it? If I have the shift motor off is there a way to test it to see if that's the issue? As for fluid level, I haven't checked the level but there's not leaking and the transmission level is correct (I'm assuming the transmission and transfer case both have tranny fluid and if the seal between the two went bad then one or the other would be too full).

 

You should be able to easily locate the wiring harnes on the shift motor. Try removing and reseating the connector and see if that helps.

There are more detailed threads about shift motor problems but I don't have the time to search right now. I'm running late.

Here is exploded view of the T-Case.

#2 is the shift motor. Only 2 bolts holding it on. If you remove that you can get a screwdriver through the hole to move #77. No ATF will drain out.

 

Here are my experiences with ESOF 4X4, but I don't know if they will apply.

• I had no 4X4, the vacuum pump never shut off, and the defrost would not switch to floor or anything else.
• I bypassed the ESOF module and everything but the 4X4 worked like they should.
• New ESOF module and everything still works, but the 4X4 was intermittent and the defrost problem returned when I tried 4X4.
• Found the vacuum lines to the hubs were cracked and leaking.
• I cut the bad section off and there was plenty of hose left to reconnect without replacing.
• All is right, whole, and complete in the world - I own the snow.

There is an electrical connector on the transfer case, it might be a good idea to pull that off, inspect it, and re-connect it. Sometimes just "swiping" the connector after 11 years of exposure to the elements does a world of good. Maybe you'll find something else just by inspecting it.

I had transmission work done once and the mechanic didn't get the connector for the transmission completely seated. The "Park" signal didn't get to the PCM, so I couldn't engage the starter 200 miles from home in the dark at the hotel. A workcoat, flashlight, and a small screwdriver was all I needed to pull and re-seat the connector and the problem was permanently fixed.

 

This THREAD has some info about T-case shifting problems. Hopefully you can get the shift motor to start working and you won't have to remove it.

Here is a Wiring diagram that covers '99-'01 ESOF

 

Thanks for all the good info. I had to go pick up one of my kids from a activity last night and I put the hubs in manual, put the dial on 4H and started the truck and the 4X4 light was on. I put the truck in neutral, said a quick "come on baby" and shifted the dial to 2H. It worked, 4WD disengaged. I got out put the hubs back to auto and will hope it doesn't snow much more until I can get it fixed. Considering that the auto portion of the hubs stopped working last year I'm thinking I might start with vacuum. I still think though there's there's something electrical between the dial on the dash and the shift motor. When I get some free time I'll go unplug the wire to the transfer case and spray some electrical cleaner in there. Anyone have any other ideas on what might fail electrically? Is there a solenoid on the shift motor? The exploded view doesn't appear to show one.

 

Glad you are squared away for tomorrow's trip.

Check that wiring diagram I attached in post #10. There could be an intermittent fault anywhere.

I had a T-case no shift problem and the following fixed it.

Remove the 2 ESOF relays and clean the spade terminals with some emery cloth or some very fine grit sand paper. Then spray them with some contact cleaner or brake kleen. Also lightly spray the relay sockets before you reseat them.

While you have them out you should bench test and exercise the 2 ESOF relays. Pay particular attention to the normally closed contact 87a to make sure there is good continuity to 30 when relay is not operated. Supply battery to 86 and ground to 85 to make sure relay operates. With relay operated there should be good continuity between 30 and 87. By exercising I mean operating and releasing them mutiple times very quickly.

 

It's been a hectic summer and I'm finally getting around to working on the 4x4 problem with my truck. Here is what I've come up with. I've checked the operation of the switch on the dash it's operates as it should. I pulled the relays and exercised them as @paysonPSD instructed. I heard the click of the relay as I put power to them so they seem to working okay. I was not able to get a continuity reading between 30 and 87 terminal, however, I'm fairly certain I didn't know what I was doing. I set a volt meter on 12V and then touched the probes to the two terminals. Got nothing from all four relays (cleaned and bench tested the trailer ones too). I tried it while the relays were engaged and not. Once I did all that I turned the key to run and tried switching to 4WD. No light on the dash, and no clicking from what I could tell. Tried it in park and neutral. Then I did the same with the truck started and idle and then while moving. Still Nothing. Next I crawled under the truck to check on the plug going to the motor that shifts the t case. Plug looked okay and actually pretty clean for 205,000 miles. Sprayed electric cleaner in terminals.

That is as far as I've gotten with testing. But I noticed another thing. A wiring harness at the top of the shift motor thing. I traced it back, it connects up to the transmission range sensor. I replace that about a year or more ago at the suggestion of someone on here (can't remember maybe Pete, he was in Seattle or Portland). The reason for replacing the range sensor was because the truck wouldn't start with the key. Still doesn't. I've installed a push button start that just jumps the starter solenoid. At the time I was talking to him he said it was something between the ignition and the range sensor that cost about $300. Starting with a button was good enough for me.

While looking for more information on fixing my 4WD problem I came across some post dealing with the GEM. Apparently, it controls things like starting and engaging the 4x4.

Does anyone know if that may be the culprit? If so how do I test it? It appears to be about $300 for a new one so maybe that's my issue.

Also, how do I test if the shift motor at the t case is getting signal when the switch is moved from 2H to 4H, etc? And can I test it with the engine off and the key set to the run position? If it's not getting signal then the problem is between the switch and the t case. Considering I didn't hear a click form the relays (I was in just sticking my head out of the cab though) it may be between the switch and whatever comes before the relays, yes?

 

Forgot to mention, I'm not having any other issues with the GEM like wipers coming on randomly, lights staying on, etc.

 

dunno if this will help much but i just went out to fiddle with my esof stuff with these results...

i can go from 2h to 4h all day long back and forth without missing a beat.
the auto locking hubs will not engage by switch due to a bad selonoid valve.

manually they lock just fine.

if i try to drop into 4L i get a click, clunk... then nothing, and im in 2h.
after i try going to 4L i lose all function of the switch until i shutdown, pull out the key... then restart. again...
cycle between 2h and 4h till the cows come home... but lose all functionality as soon as i attempt a 4L engagement.

no low range light anytime i try to engage it... but it flashes at startup.

yes i have checked the front driveshaft to ensure the 4x4 light isnt lying to me.
locks up good in 4h. spins free after i try 4L.

im on dry hardpack, but shouldnt it engage regardless of the surface im on?
especially with front hubs disengaged?