2004 Dakota, 3.7L, 4x4, 5 speed with 124k miles.

Backstory:

Got stuck in some snow yesterday and put it in 4LO to get out, drove around in 4HI afterwords since the roads were covered. Left it in 4HI overnight after parking it.

Today I tried putting it in to 2WD after driving briefly in 4HI and was met with a grinding noise that seems to be coming from the transfer case. The noise frequency is proportional to speed and is present even when coasting in neutral. There’s also some vibration in the shifter **** that wasn’t happening before.

4HI and 4LO seem to be working perfectly
fine with zero noise.

So far my guesses are either that’s it’s not shifting in to 2WD property (vacuum line?) or that there’s an issue with the output shaft snap ring.

Any better guesses?

 

2004 is electric shift, there's an electric motor attached to the tcase that moves the shift forks around.

That you aren't getting a flashing light for encoder/motor faults is good. I also believe these are chain-driven cases. The driveline is full-time, so the front driveshaft is always spinning, the chain sprocket is just disengaged in 2WD. \

I don't know exactly how the engagement mechanism works, but i'm wondering if it's just dragging enough to make noise.

 

Drove around in the snow a bit today and realized that it’s just the rear wheels spinning when switched either to 4HI or 4LO.

so basically:

2WD = light grinding/rubbing noise
4HI = no noise, only rear wheels spinning
4LO = no noise, only rear wheels spinning (it seems)

 

To preface this, I dont have a lot of experience with the dakota's t-case, as I just bought my first, but I do have a few salt rotten vehicle resto's under my belt so far.
First things I'd check is if snow is it's packed up tight around that shift servo, hub/brake assembly, etc, it could potentially be causing binding for that servo fork shaft to do it's job. For that reason, before doing anything, I'd get it inside somewhere warm and thaw it out, even if it's a self serve carwash. Spend a few bucks, blow off some sand and salt, and if the wash water is heated, it'll help you get any packed snow out of those frame/body cavities you may need to access.

Once the vehicles warm(leave it somewhere heated overnight if possible) and you know t-case fluid levels are good(check using the top fill/sight plug on t-case), try throwing everything in neutral before shifting 4lo, give it 5-10 seconds before shifting to gear, roll the vehicle forward under its own power and see if front tires engage, this part is much easier if it's securely placed on heavy jackstands or a 2 post lift. Repeat same steps for 4-high.
If they engage, something was likely bound, or viscosity change from the cold may be the culprit. Trans oil, like brake fluid and PS fluid does tend to retain and hold some moisture over time as it usually doesn't get quite hot enough, especially here up north, to completely evaporate like it does in engine oil. If the fluid is old and dirty, it may be worth changing out, if it's milky or frothy looking at all, definitely change it out and inspect for any leaks/damage.

I know these are all obvious suggestions, but they're often overlooked and lead to unnecessary spending/parts replacement because a little dirty fluid froze up. I see it a lot here in the upper midwest.

If the basics don't cover it and the front wheels still don't engage in either lo or high, I'd definitely suggest having a shop take a look. It could be something simple, could be hubs not fully engaging/disengaging, chain stretch, servo, any of the things Magnet suggested, and so on.

Good luck and hopefully it's something simple!

 

As Magnet said, it is electric shift. The shfit mechanism is internal to the transfer case, nothing is exposed to the outside so water/snow should not be an issue.
The front output shaft is chain driven.
There is a "mode" sensor that determines what position the shift motor is in.

From the FSM: Operating ranges are selected with a dash mounted shift selector switch. The shift selector switch provides an input to the Transfer Case Control Module (TCCM) to indicate the driver's desire to change operating ranges. The TCCM uses this input, along with input from the transfer case mounted mode sensor and information from the vehicles bus, to determine if a shift is permitted. If the TCCM decides the shift is permitted, the TCCM controls the shift motor, mounted to the exterior of the case, to perform the shift.

 

What confuses me is that he is not getting the flashing error light that normally results from the mode sensor and shift motor not agreeing. That tells me the mode sensor thinks the motor is in the right spot, and something is wrong internally. But I don't know how the clutches and forks are set up.

 

I agree Magnet. It sounds like there is something wrong internally. Possibly it is an issue with the mode sensor so that it isn't fully engaging the shift motor and that's why no error light.
The shift forks are set up pretty much like any manual transmission.

Or, it could be an issue with the front axle or CV shaft.

Time to jack up the truck and see what is really turning and what isn't.

 

Did you check to see if the front driveshaft is damaged? Check the U joints as well as both yokes. Its possible you broke something off of there. It would explain the lack of movement in the front with no errors.