Toyota 4Runner OBD1 Codes Code 51

I Got A Code 51 On My Cel. How Do I Fix That Problem? Also My Trans Work In Park-reverse-neutral But When I Put It In Drive-2-low My Trans...

Trouble Code 51 Came Up In My Wifes 4runner I Just Don't Know Where To Start Trouble Shooting With A Code That Broad Any Help As To A...