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. 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. 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?. thank you guys any help would be appreciated. this is really frustrating!

 

My guess is a shift solenoid.Find it on the transfer case, unplug see if it stops. If it does then its a control issue.

 

but isnt a shift solenoid in the transmission to switch from 1/2 3/4 and not the tcase. i have no problem with my tranny at all, just had it rebuilt. shifts a little hard but i think thats from the shift kit. im 95% sure it is the transfer case because it doesnt grind when im in 4wd. would you happen to know where the tccm is

 

is the sound from the diff or the tcase?

 

As I said guess. There has to be "something" my guess is solenoid to engage the transfer case. Yes you have shift solenoids in the tranny.