loud grinding noise coming from transfer case

[ph4ze]

Hello guys i have a 96 4dr tahoe 4x4. the other day i was going down the road at about 80 mph, came to a stop light everything was fine about 5 10 minutes later i heard this grinding noise. i thought it was the power steering pump because everytime i turned it would make the noise. i could also feel the strain in the steering wheel. well i decided to put it into 4wd to see if the problem still persisted but it didnt. so thats when i found out that my truck is trying to to go into 4wd without my input when its in 2wd. i took my front driveshaft out because i thought the grinding was coming from the differential. so now when i have it in 2wd i dont feel the strain on my drivetrain in the wheel when im driving but its still trying to go into 4wd and grinding. i know these things are controlled electronically. i was thinking maybe the 4wd vacuum actuator on top of the tcase is bad but when i looked at it, it had an electrical line on top i thought this was controlled by vacuum?. is it possible that my transfer case is going? and is the transfer case controlled all by electrical because i cant seem to find any vacuum lines at all. thank you guys any help would be appreciated, i cannot find anything on the internet with help on this subject or the think it a wheel bearing or something but its not because i can hear the noise coming from the middle of the truck in the tcase. i had this same exact problem in my blazer. i hate this electronic crap. this is really frustrating!

 

[SunlitComet]

do you have push button selection or floor shifter? and the shift selector is on the left side regardless. the electric switch up top is for the powering the electric actuator in front when shifted in any 4wd mode. if you removed the front shaft and it grinds in 4wd regardless. the t-case must be torn down for inspection.

 

[wma4553]

The grinding noise might be the rear output shaft bearing which has a cheap plastic retainer ring that fails. You can pull the rear output shaft and look up in the case you can see the bearing, if its the problem some of the balls will be missing. There are rebuild kits available on ebay which include all the bearings, gaskets, ect.(make sure the kit that has an aftermarket rear bearing that is all metal.) there are also how tos on the internet. The rebuild is not that difficult, the hard part is getting the thing out and back in. I did mine about a year ago and spent about $150.00 on parts. I did mine laying on the ground by myself and it was a *****. It would be much easier if you have a lift and transmission jack, if not at least get a helper.