stuck in low lock

[Crazy Dad]

Today I went out to move the big trailer and was forced to utalize 4 while drive in low lock. All went well until it was time to take it out. Presently it is stuck in four wheel drive and wont come out. Can anyone point me to an easy fix. The help would be appreciated.

2001 Ford F-350, 7.3 w/automatic transmission

[dieselcrawler]

Could be a few things... "drive train wind up", as in pressure on the drive train that might come from making a turn in 4wd, and not going straight/back the other direction a little bit to releave the tention that comes from the front wheels needing to travel farther than the rears. Could also just be your shifter linkages need lubed, if it's manualy shifted, or if it's got the knob on the dash, it could be part of that system, I'm not farmiliar with it...

I would: unlock the hubs, and drive in a straight line a few feet, and then back up, goosin' the fuel, tryin to spin the tires a little, maybe 2 or 3 times... then, with the trans in neutral, try to shift back to 2 wd. if you can't get the hubs unlocked, you can still try the same thing, on grass or gravel either way. I always put the trans in neutral when shifting the transfer case in any truck... easier on the truck that way.

If it's the manual linkage, have someone inside the truck try to shift it for you while you watch from under the truck... BE SURE TO CHOCK THE WHEELS, THE TRUCK MAY ROLL OVER YOU! check it out... let us know what happens... good luck!

[jfines@cox.net]

Check the vaccum system. That is how it is engaged. Something could be stuck. Although if the vaccum failed I would think it would shut off.

[wingnut]

im guessing you have the vacuum operated system (switch on the dash, not the manual shift lever) as i had this same problem when i bought mine. im also willing to bet you have not used 4 lo for some time.

dieselcrawler has the right idea, but its not your hubs that are the problem...its the Tcase. the engagement "spline" (for lack of a better term) has not been used for awhile and is lacking any sort of lube whatsoever.

if all the above is right, then the "back up and goosin it" as crawler mentioned should do it. if not, i had to goose it in reverse, pop it in neutral while still moving and then get on the brakes pretty firmly, wait a few seconds after the truck stops, then shift to drive and let her ease forward. after the 2nd time she came out easily!

then of course you need to get out and use the 4 lo once in awhile to keep this from happening again

[Crazy Dad]

Thanks for help everyone. I going outside to test each of your theries.

I do appreciate the help.

[Dave]

Is the trans in neutral when you are trying to shift out of low?

[Yoslick]

Foots gotta be on the brake pedal! to go into low, probably out as well while in neutral.

Slick!

[alabamafrog]

Got to be in neutral and foot on the brake before it will shift either way. The T-case is completely separate from the front hubs. The light on the dash has no way of knowing what the hubs are doing, only the T case. The hubs are vacuum latched and unlatched. The vacuum is not constant. It sends a pulse of a certain pressure to latch and another pulse of a different pressure to unlatch. The pulse lasts about 30 seconds or so after the dash switch is moved, the pressures are as best I can remember 6” and 15”. There is a solenoid on the fender that regulates the pressure and operates the hubs. All of this system can be easily tested with a hand vacuum pump/tester. Again, if the dash light is staying in 4x4 low then it is something with permissives or T-case actuator, if the hubs will not cooperate and the T-case and dash lights work right then it is the seals or vacuum system. It is a good idea to periodically reach in and make sure both axles turn free when in 4x2

[wingnut]

forget the auto hubs...they were on my truck only long enough to get it home...they now reside at the bottom of lake hogan

[alabamafrog]

Some folks really like the convenience of having the auto hubs, they can be repaired and maintained.