Hey guys my trailblazer is making a weird ratcheting sound out of nowhere driving down the road it's in the passenger front. I also can't lock the trailblazer in 4wd. What could it be? Thanks Guys

 

Does your transfer case lock/unlock with a lever on the floor or is it electronic on the dash?

Could be your 4X4 Actuator motor. Some thread into place, but I think yours bolts on. Could be a bad switch too, if its on the dash.