some time ago my 4wd engaged by itself at high speed and now i get a grinding coming from what sounds like the front right wheel. also, when i put it in 4wd it will not turn to the right or left very far. i know the vacuum switch is bad but i need to know what other damage may have been caused from the 4wd engaging like it did. by the way, the 4wd still engages by itself once in awhile.