Is there a mechanical reason why I wouldn't be able to lock the center diff? It was frozen when I got the truck and blindly spraying some PB Blaster up at the linkage on the transfer case freed it up. I haven't used it in some time and tried to lock it a couple weeks ago but no go. I repeated the lube attempt on the T/C side linkage as best I could, but the stick is binding and only moves about 3/8" to the left. Today I removed the console, undid the four bolts that hold the selector up to the tunnel plate and lubed the selector end of the cable mechanism. Still binding. There were no incidents that would make me think there's an actual problem with the T/C itself, the truck drives fine without any vibration or noise. Is there something internal that could be preventing it from locking with no other side effects? The Hi-Low cable and linkage are fine, for what that's worth. I tried locking it stationary, rolling a little in neutral, all the tricks that help with the Hi-Low.

 

Check your transfer case fluid level, if it low or non existent it can be impossible to shift. Does it move at all ?

 

It moves about 3/8" to the left but binds. I've driven about 2.5k miles since I first noticed it binding. Would low fluid manifest itself as other issues in that time period? I don't remember checking the fluid for some time, so that's a good idea.

 

@ahab Apparently they will chug along happily with very little fluid then finally stop with little warning. Mine gets notchy when it get's about a cup low.

 

Will check it, thanks for the advise.

 

The shift fork in the case is spring actuated in both directions so if it was an issue with the dog clutch itself, you would still be able to move the shifter I think. Makes me think its the lever on the top of the TC again, or maybe a cable issue.

 

I agree with you. When I installed my CDL I got a used cable that had a split on the outer layer, I patched the cable and put lots of WD40 and it worked outside the car with some resistance. After test fitting it would not move or shift the gears and binded up even when I moved it so the cable was relatively straight. I recommend taking the shift lever out and testing the TC second (of course checking/filling TC first). You can access it from below or through the center console with a 10 mm wrench and manually engage the CDL.