1981 F250 4x4 not shifting into 4Lo

delco1946

delco1946

Senior Member
Hi All,

I just bought a 1981 F250, trailer special. Its a beefy truck with 4x4. I'm just staring to play with it, but it wont go past 4HI (in the transfer case). The mechanic who inspected the truck before i bought said the fluid was dirty. It seems that either two issues are happening 1) the truck wont "let" me shift into N or 4Lo because it thinks the needed requirements have not been met OR i am meeting those requirements and the transfer case itself (be it gears etc) are sticking, damaged etc. The requirements to shift into N and 4Lo are that the automatic transmission needs to be in neutral, and the truck needs to be stopped (foot on brake so i assume there must be some sort of brake activated switch). Hubs need to be locked of course. Does anyone have any ideas/experience as to where to start looking first?? Thanks!-Christopher
 
Some of the older ones I'm familiar with can get crusty and the shift lever will seize up on the fulcrum pivot shaft. It has to come apart & be cleaned if that happens. There is a locking feature too. If I remember correctly, you have to push down on the lever to get it unlocked so it can pivot on the shaft.
 
I was pushing down and getting pretty rough with it, but maybe ill try again. I just dont want to break anything :/
 
There is a plastic snap on type bushing on most of these where the lever attaches to the shift arm. If you have to remove the shifter mechanism to work on it be careful not to break it. Replacements are hard to source for some reason. They are a b!tch to remove. A tie rod puller may work. I think there is a you-tube video on this subject out there. If you can get penetrant on the fulcrum bearing area of the shifter (plastic wear bushings in a steel tube), you may be able to get it to pivot again but it might not do any good. That stuff being under the floor makes it vulnerable to corrosion and whatever lubricant, if any, is likely long gone.
 
The plot thickens...this must be some sort of electrical or vacuum issue - I'm guessing related to some sort of switch that tells the system I'm in neutral and stopped. I have twice been able to go into (transfer case) neutral and then 4Lo with the truck off, and the key in accessory position. The 4x4 lever moved smoothly (suggesting that the mechanical linkages are lubricated or a nonissue). anyone know what/where these switches might be and if they're an electrically activated switch or vacuum activated?? I can't find any references in my manual, repair guide or online. Im going to load a picture in a bit i took showing some wires sticking out of my firewall near the brake pedal, hoping someone might know what they should be connected to (fingers crossed its as simple as someone disconnecting a wire harness but the wires could also be for a trailer hookup too). Any help/ideas is appreciated!
 
In the center of this pic is a grey wire connector....hanging in the breeze, no idea what it is supposed to be connected to...
 

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You have an automatic transmission but it is interfaced with a standard shift transfer case. Most of the older trucks with manual locking front hubs are all manual operation. The transfer case can NOT be shifted while you are moving since you don't have a clutch so you have to shift the trans into neutral to get the shift. If you are parked on a hill then getting the transfer case to shift might be a problem. The gear train has to be slack to get an easy shift in the transfer case. It's best to have the drive train relaxed on a flat surface to shift it. The hubs have to be locked in anyway to use the 4WD features. They may use a light on the panel to tell you it's in 4WD but I doubt that there is a lock out. I could be wrong but I'm talking from experience with 4WD vehicles in that time frame.


If your truck was used for trailering than it may have had an electric trailer brake system. Other than following the wires or consulting a factory shop manual for your model then I can only speculate on that as far as the flagging connector plug going nowhere.


There should be a 2WD selection on that shifter too. It is usually on the Hi side of neutral for the transfer case. Go through N to get to the 4WLo side. It always depends on who made the transfer case. The Ford Truck Forum may be a better shot at getting info about your new to you acquisition.
 
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