I'm having all kinds of problems with my 4wd SOTF. First, nothing happens when I turn the **** for 4H or 4L, no dash lights no click. My SS both have fire to them (12v) & both have vacuum, but the right one (facing truck) is sending vacuum to VSM on front axle housing & it disengages Axles from front driveshaft but does not disengage hubs. I have searched the hubs & inner wheels area & cannot find anything except brake lines & something that looked like a vacuum line but as it traveled up to engine area turned out to be 2 wires.

Also , I have no ground to left SS no matter what position the switch is in as well as no fire (+VDC) to any pin on TC connector. All fuses show good. Anyone know anything about these issues? Please help!!! I've been down now for 3 weeks, am disabled but not stupid so please don't talk down to me.

 

The 97-03 F150 does not have hubs that disengage. The front axle will ALWAYS turn. The disengage is at the diff, so if the front driveshaft is not turning, the fronts is disengaged.

 

Thanks Kingfish51!! In other words the axles should turn anytime the front wheel turns? Thanks for the quick reply!!! Do you have any idea about my other issues such as no voltage to TC & no ground to Engage SS? Thanks again!!!!

 

With no power to the transfer case, it could be a problem with the GEM module (which sits under the fuse block) or a bad fuse. Take a look at the owners manual (if you do not have one, you can download one for free from http://www.motorcraftservice.com/vdi...&menuIndex1=13) and verify that all the fuses inside and under the hood that control the GEM and other drivetrain parts are good. There are quite a few fuses that are used by the GEM module.

 

Thanks again for the quick reply!! I rechecked all fuses & all show good except #20 that has no fire to or from it. The fuse is good but nothing to it. My Manual shows it to be PCM, GEM & CTM. But, I've seen posts on here that claim that this is for manual trans only & some say that's not so...what do you think?

 

Can't say for sure, but since it does send power to the GEM, it may be the problem. And since the PCM is the computer, it makes me wonder.

 

Does anybody out there know for sure??????

 

One thing you can check is the GEM and fuse block. They are known for corrosion, causing this kind of problem. You will need to pull them out.

 

Why did you start a new thread? You just broke all troubleshooting continuity.

https://www.f150online.com/forums/el...al-manual.html

 

I started a new thread because the other one played out or at least seemed to. I have been down for quite some time & hoped starting a new thread would generate some new help, which it did. This is my only vehicle & I live several miles from the nearest Dealer even if I could afford them. I am old, disabled & living on a VERY fixed income & I joined just seeking some trouble shooting help. Sorry if I broke a rule.

 

I understand your not up with the descriptive terms.
This makes your post hard to follow.
What year are we trying to help you with?
Instead of using fire use Power.
What is SS?
What is VSM?
.
Electronic Shift on the Fly ( ESOF)
The system has a lot more complexity than your realizing.
Here is a short course on how the system works.
1. The dash switch signals a Module under the dash called a Gem.
2. The Gem operates a motor on the rear of the transfer case to a 'first' position.
This signals the firewall solenoids to route engine vacuum to the front axle 'actuator'.
3. The 'actuator' pulls a link into the axle housing to slide a collar locking the drive so the front wheels are driven from the transfer case.
Once this occurs the dash light come on as 4H.
.
Only difference with 4L is the transfer case motor moves to it's second position and shifts case to a low gear ratio and the transmission shift speed sked is changed.
.
If nothing works, it can be power, the transfer case motor or the GEM module under the dash or even harness plugups, fuse etc..
Be sure the case motor has power when the switch is engaged.
A relay will pass this power unless the relay is not signaled to do so then that is a problem.
Look at the possibility the GEM has gotten wet from a leaking windshield and has corroded.
It is located on the back side of the dash fuse panel.
.
I'm not sure of where your failure might be from you description so far.
.
You now have the operating layout to help see the failure area by observation and testing and how it acts or doe not act..
Good luck.

 

Thank you Bluegrass for the operating layout, it helps alot!! Sorry about the discriptive terms but they seem to keep changing. I was told SS stood for shift solenoids, +VDC was fire or current & when I used the term vacuum actuator on the front axle housing I was corrected & told that there was none but instead it was a VSM (vacuum shift motor). I'm not intentionally trying to confuse anyone. Once again, I'm sorry!!
Here is where I'm at; I replaced the ESOF switch in the dash, checked all fuses, checked the shift solenoids, checked the front axle actuator & they were all good. I have no leaks in my windshield or door glass & the GEM connections look good. I have no power to the transfer case whatsoever. I was told to check the dark green wire with the light green stripe and there is no such color wire on the transfer case connector so I checked every pin in connector, first with testlight and then with multimeter. I was told that the crossmember was no ground so I ran a groundwire from the battery.
Is there a relay somewhere between the GEM & the transfer case? If so, where is it located? Thanks for any help & I promise if we can resolve my problem I will not bother anyone on here again. I know that there are alot of Great Folks on here that are very knowledeable & my thanks & respect go out to all of you.It just seems like I can't "fit in" and I don't want to cause problems or confusion.
One other thing I wanted to add that may or may not help; the other day I decided to reset my computer & when I removed the cable I forgot & left the ESOF switch in the 4H position & when I restarted my truck 15 mins. later it was engaged in 4H with light on in dash as it should be. Problem is, the switch had no effect on it & I had to remove the battery cable & move the switch to 2H in order to return to 2WD. Hope this helps!

 

You are a bit too sensitive if you feel like you don't fit in because I corrected you for not following proper forum protocol. There are others around here (and in ALL forums) who would be a lot more rude about it. I'm a grandpa too, and we are never too old to learn.

 

No, it had very little to do with your comment. I am still trying to backtrack the current of power ( where I'm from it would be phrased tracing the fire backwards) from the transfer case. Do you know if there is a relay between the transfer case & the GEM?

 

Hang in here grandpachuck.

Find fuse 104 a 30 amp square maxi type located in the engine bay box.
Standing at your fender, it is the 'second row' of square fuses from you, the last one on the right.
Take it out and test with meter and test for power to it's hot side terminal,
as a start.
Yes the front axle actuator has the term motor in it but there is no motor action of any kind. It is purely a vacuum diaphragm housing that moves a link in and out.
No power to it, nothing turns.
Don't worry about fitting in here.
I don't fit well either because I tell it like it is and it ruffles some feathers at times.
They either get use to it or go away because I have expertise to offer help.
I don't go looking for problems either but will do battle if it's worth the effort which it seldom is anymore.
Let us know how you make out because we can run with you until you get to the faulty point.
Would you be kind and offer the year of the truck.
The color codes don't always stay the same from year to year.
Good luck.