92 Sierra Stuck in 4 Hi

Chris86 · December 20, 2017

My 1992 Sierra dies not seem to want to disengage from 4-Hi.

I attempted to back out of my driveway in 2-Hi and could not get through the snow bank, so I popped it into 4-Hi, got through, and decided to drive 3.5 miles in 4-Hi before switching back.

It did not want to switch back after the shifter was in place for 2-hi. I can get it into 4-low and 4-hi, just not 2-hi. I completed my errand and returned to my camp, drove about 12 miles in total like that.

I've checked all my fuses, and once day breaks tomorrow I will check to see if the back tires are spinning while in 4-hi.

Is there anything I can do to coax it back into 2-hi? What are the potential causes to this? I am at my camp right now and far from any garage. I would have to hit highway to get to one, and I don't want to do that stuck in 4-hi.

Any help would be greatly appreciated

Chris86 · December 20, 2017

Okay, I have been reading all I can about solutions all over the place, and came across this advice on a 4Runner forum:

Put it in reverse and back it up about 20 yards, then try to re-engage the shifter into 2-hi.

I did exactly this, and now as I would pass the shifter over the 2-hi slot it would give off this very low grinding or rubbing noise which was not happening on my previous attempts. I had to pass over the 2-hi Mark a couple of times, each time producing that sound, before I felt it bite and the rear wheel lights flash on, with that damn 4x4 light going off, thank God. Took it for a little spin and all is well.

I now have the fear to never put it in 4x4 again. Is there something that can be causing this? I am not accostomed to these GMC trucks so I have a lot to learn. I know the transfer case has low mileage and the fluid is topped, other than that I don't know the systems history.

Logan Lanfear · December 21, 2017

What happens when you try and shift when the truck is in nuetral or not running at all? Im not super familiar with these cases but I believe that they are NP241's. Sometimes they have problems with the drive chain slipping or fluid levels being low when in use.

Chris86 · December 26, 2017

I was googling around and it does seem that the transfer case is an NP241

When this first happened, I would be in Park or Neutral when I was trying to disengage the 4-Hi and go into 2-Hi. It took at least 2 dozen attempts to get it back into 2-Hi. The only thing happening I guess would be the shifter would be very stiff when I'd move it up to the 4-Lo area, and the light grinding noise when I'd pass the shifter just over the area after(going up) the 2-Hi area.

I said I had the fear to put it back into 4-Hi, but this morning we got another huge dumping of snow, so I decided to brave it. And again I had the same amount of difficulty in re-engaging it back into 2-Hi after getting back home. Backing up about 20 yards and shifting seemed to work last time, but not this time. In the end I noticed that the grinding noises that seemed to accompany being able to put it back into 2-Hi the first time were not there. So I just drove it forward a few feet, then backed it up a few feet, shifted, nothing. Repeated the foward and reverse then stop a second time and the grinding noises were back as I'd shift, and it finally locked into 2-Hi.