This morning I start up and put into drive and everything is normal. When I get to a stop sign and hit the gas petal the rpm's go up but will not move. I go to 1st 2nd and 3rd gear and still not moving. When I go shift into reverse I have a grinding noise that sounds like a manual transmission grinding the gears. I put it into 4 hi and get rolling and then switch back to 2 hi and everything is now normal. Any ideas? Oh, I have a 99 blazer lt 4wd.

 

Could this be the encoding motor?