i have a 91 1500 4x4 with 5.7litre. for the last year or so ive had lots of trouble gettin my truck into 4wd. it only goes in sometimes (not often) and recently it took me like a day to get it to engage and worked for a day then wen on my way home from work it randomly disengaged out of 4wd. both the transfer case and front dif are full with new fluid and there does not seem to be an issue with the linkage going from my 4wd shifter. it seems to move and engage fully when you work the shifter. any ideas? any commone problems with these transfer cases?

 

So if it's me testing this system, I need to know some things. First, floor shifter or electric shifter for the transfer case? Either way, put it into 4x4, drive it 5 feet then lift all four wheels up into the air. Put the transmission into neutral, and start the truck.

Spin the left from wheel. If the front axle is locked in, the right front wheel will the opposite direction as the left front wheel. If the axle is not locked in, the left front wheel will spin and the right from will be stationary. Next, lower the truck back onto the ground, and turn the truck off. Put the transmission into park and lay under the truck and try and turn the front driveshaft by hand. If it turns freely, the transfer case isn't going into 4x4 mode. If it doesn't turn, then the transfer case is for sure in 4x4 mode.

Diagnose each actuator from there. Be it the front axle actuator, or the transfer case encoder motor (if it's electric shift) this will identify where you need to focus your efforts, because either or both of those two item can keep you out of 4x4.

Good luck!

 

I was so going to suggest, if it is floor shift.... Check your cab mounts that they are not going bad. If the cab is moving on the chassis your linkages will be out of adjustment

 

my thing is that wen it says its in 4x4 it definatly is and wen it says it isnt it def isnt. it really seems to work perfectly fine once its engaged, although it has disengaged aftr engaging before. (but the light went off and came back on once i felt that it was engaged agian).so im gona assume i dont need to test it to see if it is actually engaging and disengaging because it absolutly feels that way and seems to work/ not work wen it says it is and isnt.
it is a floor shift. i think the linkage seemd ok, but any suggestions on a proper way to adjust it? so i can be sure.
i will also check the cab mounts too.




also i once heard that the transfer case in these trucks are notorious for stretching chains? could that be an issue? iv never been inside a t case so im not %100 sure whats all happening in there exactly.


thanks for the suggestions fellas

 

As far as I know, the only thing that really goes wrong with these trucks that have the manual 4x4 transfercase, is that the front actuator goes bad and doesn't lock in the right side axle. If I recall correctly, the light on the 4x4 shifter will light up when there is a good signal being sent to the front actuator. Weather the actuator is actually working or not is another story.

So if the light stays out and stays out, I would think it's a circuit issue or that the actuator is going bad internally, and if the light is on, and the transfercase shifted into 4x4, but you still don't get 4x4, I would replace the actuator on the front axle.