Need a little HELP! Grinding noise in 4WD :(

[JAKD RAM]

So I go to put it in 4 High yesterday since it snowed and all of a sudden there is a grinding noise coming from either under or the front end somewhere. Almost sounds like gears grinding. This only happens when it goes into 4x4, and when I turn off 4x4 the light goes off but the grinding still goes on until I hit a bump or something or go into reverse then it stops or feels like "disengages" but when the light goes off it's not in 4x4 (I could tell turning on dry pavement 4x4 was not on)? I got under it today, added gear oil to the front since ti was low, looked at the U joints, everything seemed to look fine, wiggled everything around, spun the driveshaftand didn;t see anything besides I might need a new front left wheel bearing down the road since it has some up and down play slightly. BUt again the noise only happens in 4x4, no noise in 2wd. So any ideas? I guess I need to get 4 jak stands and jack it up, I only have two at the moment but i'll have to find 4 and that way I can narrow down the search. I am HOPING it's not a bad transfer case. Any help is greatly appreciated.

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[JAKD RAM]

Forgot to mention. My "ABS" light and "BRAKE" light have been on for about a month. I replaced one speed sensor but i guess theres some other one I'm not finding that needs to be replaced. Didn't know if could by some chance be intertwined one problem leads to another and vise verse? Anyone know what sensor I need to replace to get those lights to go off? Auto Zone gave me one, I replaced it and same lights still on. SO I am guessing theres another one or I replaced the wrong part?

[Skab]

I think the sensor you need to replace is the one on the rear differential from what I've been reading here on the forums.

[dhvaughan]

the front end grinding has nothing to do with the ABS and Brake Lights. that's most likely one of the speed sensors, either the one in the top of the rear diff (most likely) or the one on the trans/t-case tail housing.

the front end grinding could be the t-case, or the diff, or the CAD coupler. most likely its the CAD. the best way to debug it is to put it up on 4 jack stands and crank it up. with an assistant to hold the brakes and operate the shifter, you can better tell what its doing, and where the noise is coming from.

read this whole thing.
http://www.dodgeram.org/tech/repair/..._engagment.htm

then test your 2 vac lines at the cad.
should be strong vac on one in 2wd and strong vac on the other in 4wd. without this, it won't work.
once you have vac, move to the CAD itself and take it apart and check the shaft for rust/sticky. its not overly complicated and usually just needs cleaning. finally check the sliding coupler that it easily moves from side to side and over the inner shaft to couple the 2 axle halves together.

the most common problem is a cracked or missing vac line between t-case and cad. easily fixed with new rubber line.

if you've got vac, and don't want to take it apart. shift it like this..
stop.
shift.
slowly move forward or backward and give the coupler a chance to slide into place.
clacking or grinding is bad... so go easy.

when you get tired of working on it, get a posilok manual cable.
it took me about a year and two different fixes for me to get tired of it.