trans speed sensor low input
 

hello i have a 99 chevy blazer lt 4x4 and is throwing a code saying speed sensor circuit a low input, today i put a new speed sensor in and the code still pops up. As well as in drive it will not shift out of 1st until i hit around 4500 rpms and when it does shift it slams into second. But will not shift int 3rd and when i slow down it'll stay in second. Also my mph gage dosent work not sure if its related. PLEASE HELP!