Ford shift on the fly - no 4HI

[austinjenna]

2010 F-360 6,4L
My electronic shift on the fly will not engage in 4 HI. It will go into 4 low, comes back out into 2HI just fine, just no 4HI. I can manually lock the hubs and it will work, just not from the dash switch. The light on the dash does come on as well if I use the shift on the fly.

Since I can manually lock in the hubs and it works I have eliminated the hubs. I tried the defrost/vent trick and it works as it should. I know these things work on vacuum and since its going into 4low I can eliminate a vacuum leak. Im just trying to debug it before going to the dealer.

Any ideas on where to look?

[austinjenna]

UPDATE - it works now.
Vacuum pump was working fine. I jumped the vacuum hoses at the solenoid, put it into 4wd and it worked just fine. I did that a few times and it worked every time. I figured I would buy a new solenoid. I hooked it back up to the original way and tried it out..it works. I dont know if something was stuck somewhere but its all good now. Jumping those vacuum hoses did something to 'un-jam' something. So I am leaving it as it is for now.

[austinjenna]

This isnt true. I had an 06. I had bad vacuum lines to the front, but it would still go into low. Basically it have me a 2wd low. I used this so the time backing my camper up a hill into my driveway. I never fixed mine on purpose. The vacuum lines up front are a common problem. Next time you put in in 4wd turn the fan up and see if it switched to defrost. This would indicate a vacuum leak.

Did that trick as well right off the bat, it does not go to defreost

[twinstick]

austinjenna wrote:

so the steering does bind up in 4LO?

Has it always done this?

Are you sure locking the hubs is not required?

You can place the hubs in 'auto lock' mode. When using the switch on the dash its supposed to be able to switch into 4 hi or low.

Since it does switch into 4 low my assumption is the vacuum lines are fine - there is only one vacuum line that runs from the pump to the hubs. I would think if there was a leak it would not switch into high or low.

What I mean by 'binding up' is that I know its in 4 low because of the low range when i drive and if I turn the wheels while driving on hard pavement the wheels will 'skip' or bind because I am on dry pavement. So I know 4 low is working fine.

if I switch into 4 high the dash light comes on but I never feel it engage. Also if I drive it slowly and turn the wheel there is no binding. I can turn the wheel the entire way and make a circle no problem. If it was in 4 high I would feel it skip and bind

This isnt true. I had an 06. I had bad vacuum lines to the front, but it would still go into low. Basically it have me a 2wd low. I used this so the time backing my camper up a hill into my driveway. I never fixed mine on purpose. The vacuum lines up front are a common problem. Next time you put in in 4wd turn the fan up and see if it switched to defrost. This would indicate a vacuum leak.

[Grit_dog]

So whether the hubs are on auto or manual, no binding while turning in 4 hi, but 4 lo locks up in either auto or manual hub? Then I stand corRected and would say it's probably the servo motor or something with the t case not the hubs.
Good luck getting it repaired

[austinjenna]

so the steering does bind up in 4LO?

Has it always done this?

Are you sure locking the hubs is not required?

You can place the hubs in 'auto lock' mode. When using the switch on the dash its supposed to be able to switch into 4 hi or low.

Since it does switch into 4 low my assumption is the vacuum lines are fine - there is only one vacuum line that runs from the pump to the hubs. I would think if there was a leak it would not switch into high or low.

What I mean by 'binding up' is that I know its in 4 low because of the low range when i drive and if I turn the wheels while driving on hard pavement the wheels will 'skip' or bind because I am on dry pavement. So I know 4 low is working fine.

if I switch into 4 high the dash light comes on but I never feel it engage. Also if I drive it slowly and turn the wheel there is no binding. I can turn the wheel the entire way and make a circle no problem. If it was in 4 high I would feel it skip and bind

[hotpepperkid]

Im so glad I have manual hubs and xfer case

[time2roll]

austinjenna wrote:
Its easy to determine if it goes into 4 low. I put in N, flip to 4low, put in D and you can immediately tell because the engine revs up when giving some gas and I am going like 2 MPH.

I can tell its not going into 4Hi using the switch because I can flip the switch drive and turn the wheels and I get no binding at all.

If I manually lock the hubs drive and turn the wheel it will start to bind up so i know its in 4wd

so the steering does bind up in 4LO?

Has it always done this?

Are you sure locking the hubs is not required?

[Ductape]

There's a vacuum valve that operates the front hubs, it operates on 12v and switches the vacuum to the front hubs. I would start by checking to see if it's switching the vacuum to the hubs on and off. Vacuum on to disengage the hubs, vacuum releases to engage front hubs. I don't know where it's located on your truck, though. You could trace the lines up from the hubs, or Google probably knows.

[Grit_dog]

A bit confusing explanation, but my armchair diagnosis is the auto hubs not working properly openly.

[austinjenna]

Like Grit mentioned above, it is possible for the transfer case to shift to 2 low, adding gear reduction, and the hubs still not locked, under the right circumstances. When shifting to 4 low, check for serious bind when turning, to be sure hubs are locking.

They are. It will bind up when trying to turn

[MFL]

Like Grit mentioned above, it is possible for the transfer case to shift to 2 low, adding gear reduction, and the hubs still not locked, under the right circumstances. When shifting to 4 low, check for serious bind when turning, to be sure hubs are locking.

Jerry

[austinjenna]

Its easy to determine if it goes into 4 low. I put in N, flip to 4low, put in D and you can immediately tell because the engine revs up when giving some gas and I am going like 2 MPH.

I can tell its not going into 4Hi using the switch because I can flip the switch drive and turn the wheels and I get no binding at all.

If I manually lock the hubs drive and turn the wheel it will start to bind up so i know its in 4wd

[transamz9]

austinjenna wrote:
2010 F-360 6,4L
My electronic shift on the fly will not engage in 4 HI. It will go into 4 low, comes back out into 2HI just fine, just no 4HI. I can manually lock the hubs and it will work, just not from the dash switch. The light on the dash does come on as well if I use the shift on the fly.

Since I can manually lock in the hubs and it works I have eliminated the hubs. I tried the defrost/vent trick and it works as it should. I know these things work on vacuum and since its going into 4low I can eliminate a vacuum leak. Im just trying to debug it before going to the dealer.

Any ideas on where to look?

How are you determining 4 low is working but 4 high is not? I'm assuming that you are feeling it go into low range is why. You won't be able to tell if the transfer case is shifting into 4 high because the speed range don't change. The only other way to tell is look under the track to see if the front drive shaft is turning while the truck is moving. Do this with the hubs in the unlocked or auto position. Fords are bad about the vacuum hubs quitting. The transfer case will shift but the auto hubs won't engage. Have you shifted the hubs manually and then tried getting on a loose surface in 4 high and spinning your wheels?

[Grit_dog]

Are you sure the transfer case is engaging the front driveshaft in any of those conditions?
With Fords, if you manually engage the hubs you get a slight bucking in the front end with slow turns even without putting power to the wheels and 4lo engaging may only be 2lo, unless you have traction tested to see if it's really engaged up front. (Note, the bucking on dry pavement while turning slow will be more pronounced if it's actually in 4wd)
Just something to check.
Can you hear the servo motor working to shift the transfer case?