my 2008 chevy 2500hd 6.0 wont engage 4wd but the front driveline locks in what gives?

If your T-case shifts correctly it will allow the solenoid to engage the front axle disconnect. If your hearing this solenoid the electronics are working. You'll most likely have to jack up the truck to check for mechanical failures if it's not one of the CV's or the front driveshaft. "my 4wd says its in and the front drive line engages but the wheels wont lock up" Are you getting power to atleast one front wheel? This is normal as they only come with an open diff, not a diff locker. They are only 3x4 at best. The front solenoid/actuator only connects/dis-connects the long axle via coupling and has no effect on the diff itself.