2005 F250 4WD PSD with ElectornicShiftOntheFly ESOF, crew cab, Lariat. Hubs typically left in AUTO but there is a MAN option as well.

Sometimes when making an 90 degree RIGHT turn from a full stop (towing and not towing), while in 2WD, the truck will feel like it is jumping into 4WD on dry pavement pulling to the left, then right, then left, then right, etc... for maybe 1/4 mile. After that it appears to be back in 2WD. Of course, when I have taken the truck to the local shop (NY Hudson Valley), the problem has not replicated itself.

Recently, we had snow and to get out of the driveway, I needed 4WD. When I flipped the shift into 4WD, the 4WD did NOT engage. I put it back into park, switched to 4WD-LO and I SWITCHED THE HUBS TO MANUAL. It did engage but it would not switch back to 4WD-HI. In fact, even after being shut off over night, the next morning it would not shift back into 4WD-HI or 2WD. I took it back to the local shop and of course by the time the mechanic got to it (several days later) there were no 4WD issues.

Reading some of the other posts, I've seen that relays, the solenoid, vacuum, etc. can be problems. Given that these issues are intermittent, where should I be looking first? The two different problems seem related but are two completely different situations.

Thank you in advance for your advice!.

 

Can't answer your questions, but on my 2006 F350 5.4l, I've had it take a while to shift out of 4lo - long enough to sit there and think "s_it - now what". It always did shift back out though. Have to be in neutral with the brake on and go to 4hi from 4lo (vs going from 4lo to 2wd).

I always keep my hubs manually locked all winter.

 

The jumping you feel.whole turning full lock in 4WD is normal.

Don't turn full lock if you can avoid it.

 

redford, the whole turning is in 2WD, but it FEELS LIKE IT IS IN 4WD.

 

I take it that you confirmed it is in 2wd.


To do so with the truck in park you should be able to turn the front drive shaft by hand.

 

Make sure the hubs are not locked to do this (have on "auto")

 

Senix, I crawled under the truck and rotated the front drive shaft to confirm that it was not in 4WD and of course, the switch was pointed at 2WD.

However, when making 90 degree turns left and right, it feels like it is jumping into 4WD. Once I straightened out, let of the pedal for a quick pause, then stepped on the pedal again, it felt like it was in 2WD.

After several of these situations in locations of little traffic, I stopped, stepped out of the cab and checked the position of the front drive shaft. It front drive shaft had ROTATED. This tells me that when I am turning hard right or hard left, that the 4WD is engaging while the shift on the fly switch is in 2WD.

What should I check next?

Seville009, the hubs are in the "auto" location.

Thank you in advance.

 

My suggestion at this point is to do some hub maintance.


Take the hubs apart and clean and regrease them


Checking all parts of course.


One other though to try first. With the heating on and directed towards the floor upon turning does the hvac default to defrost?


If so then maybe a vacuum leak is the answer to this.

 

Senix, I will check this coming weekend (my truck is at a second home).

Regarding the potential vacuum leak... Did I understand correctly that I should turn on the heat directed to the floor and when I turn 90 degrees hard right or hard left, see if the heating switches to defrost?

Thank you.

 

Yes, usually the leak would not allow the hubs to engage at all.


but it is something to check and see if that is an issue that maybe allowing them to engage and disengage.

 

Toconfirm you are not in 4wd, try to spin both front axles by hand, not just the front driveshaft. Last year when I was in market for a used work truck I ran into two trucks that were locked in 4wd. I assumed that either the locking hub wasn't releasing or the stub haft was seized to the needle bearing inside the wheel hub.

 

You may very possibly have bad front steering knuckle u-joints causing it to feel like 4WD. It is not totally unheard of for the front drive shaft to turn slightly even in 2WD. Jack up the front end (both sides) and try to turn the tires left to right at the wheel, rotate a quarter turn and try again. Also with hubs locked and wheels turned all the way to one side rotate the wheel and see if it turns relatively easily or it it binds part of the time. If they bind in any direction you probably have bad knuckle joints. The only sure way to know of course is to pull the shafts and see if they are binding but that it a fair amount of work.