Has any had this noise when going to drive?

hello everyone, just picked up a very clean 03 SR5 tacoma 4x4, just got it home, i was sitting in driveway checking out diff. lock button, (it flashes on dash but will not stay on solid, as manual suggests it wil??) any how after shutting off and attempting to move forward in Drive i get a click, cliclk, click sound almsot like lock or drive is not engaging properly, very disconcerting sound, does in reverse as well, or 4 wheel drive?? I have parked truck and will not use for wknd in case this is something more serious, (will call dealer as well) has anyone out there had a similar thing happen???thank you for your reply's
Scott

 

Is the locker button still pushed in?

 

first off i belive the locker will not work unless you are in 4 low
unless you have some mods done.....
second start the car put it in 4 high shift to gear drive foward see if it engages if not the go in reverse it should engage....

 

button is off..

 

yes have tried this as well, still to no avail..